Re: [Tutor] How to close a Tkinter window from a different thread?
On 20/04/15 04:34, boB Stepp wrote: So, how do I: 1) Check for the existence of an already open window from a previous running of the script? 2) If such a window exists, how do I close it from the new script execution? And, then, of course generate a new instance of the information window. I would suggest forgetting about windows and think about the processes that create them. Use the OS tools (via the os module) to see if the first process is still running. If so kill the process - which will in turn kill the window. You can find the process based on its name or based on its PID which you could store in a file somewhere (like in /tmp?) I feel the solution must be in Tkinter's access to the X Window system, but nothing in the documentation is *clicking* with me yet. Trying to manipulate GUIs via the windowing system should always be a last resort, it is very hard to get right. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
For randomly generating data which look like addresses, I use: > http://www.generatedata.com/ > > While it has 'export to programming language' as a feature, Python isn't > one of the supported languages. Which is fine. It can export into comma > separated values, and writing a Python program to construct a dictionary > from comma separated values is easy. > > Laura > That's a great source, and I can generate dictionaries using the other advice. If you don't request comma delimited, each record per line has | as a field delimiter, so making big dicts was easy. Naturally, I tried emailing one of the addresses - aliq...@nunc.org - but it appears to be dead ;') Come to think of it, since I used | as a delimiter, what happens if you generate a CSV file from data that already has commas in the text? -- Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Life Grid Implementation
Is my code completing the assignment??? I need some *guidance* on completing my assignment. My Assignment: A sparse life grid is used to store and represent the area in the game of Life that contains organisms. The grid contains a rectangular grouping of cells divided into an infinite number of rows and columns. The individual cells, which can be alive or dead, are referenced by integer row and column indices. The operations defined for the ADT are as follows: • SparseLifeGrid() Creates a new infinite-sized game grid with all cells initially dead. • minRange() Returns a 2-tuple (minrow, mincol) that contains the minimum row index and the minimum column index that is currently occupied by a live cell. The tuple (0, 0) is returned if there are no live cells. • maxRange() Returns a 2-tuple (maxrow, maxcol) that contains the maximum row index and the maximum column index that is currently occupied by a live cell. The tuple (0, 0) is returned if there are no live cells. • clearCell(row, col) Clears the individual cell (row, col) and sets it to dead. If the cell is already dead, no action is taken. • setCell(row, col) Sets the indicated cell (row, col) to be alive. If the cell is already alive, no action is taken. • isLiveCell(row, col) Returns a Boolean value indicating if the given cell (row, col) contains a live organism. • numLiveNeighbors(row, col) Returns the number of live neighbors for the given cell (row, col). The neighbors of a cell include all of the cells immediately surrounding it in all directions. My Attempt Code: class SparseLifeGrid : Cell = ["row", "col"] def __init__( self ): self._rowList = [] self._colList = [] self._cellSet = set() def _binarySearch( self, target ) : low = 0 high = len(self._cellSet - 1) while low <= high : mid = (high + low) // 2 if theList[mid] == target : return (True, mid) elif target < theList[mid] : high = mid - 1 else : low = mid + 1 return (False, low) def minRange( self ): return (sorted(self._rowList)[0], sorted(self._rowList)[0]) def maxRange( self ): return (sorted(self._rowList, reverse = True)[0],\ sorted(self._colList, reverse = True)[0]) # Clears the individual cell (row, col) and sets it to dead. If the cell is # already dead, no action is taken def clearCell( self, row, col ): for item in self : if item == Cell(row, col) : self.remove(item) def setCell( self, row, col ): LIVE_CELL = 1 Cell[row, col] = LIVE_CELL def isLiveCell( self, row, col): return Cell(row,col) in self def numLiveNeighbors( self, row, col ): surround = 0 if self.isLiveCell(row + 1, col) : surround += 1 if self.isLiveCell(row - 1, col) : surround += 1 if self.isLiveCell(row, col + 1) : surround += 1 if self.isLiveCell(row, col - 1) : surround += 1 ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
On 20/04/15 04:49, Jim Mooney wrote: Come to think of it, since I used | as a delimiter, what happens if you generate a CSV file from data that already has commas in the text? The CSV format covers that eventuality: You put quotes around the item with the comma. And if there are already quotes? And if there are newlines inside one of the fields? Its all covered in the CSV spec. Which is why you should use the csv module to work with csv files, it knows how to deal with these various exceptional cases. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Life Grid Implementation
niy mor writes: > Is my code completing the assignment??? Does it meet the requirements when you (and other people) run the code? > I need some *guidance* on completing my assignment. Can you be specific about what you don't understand? If you don't understand the requirements, that is best discussed with your course supervisor, not us. -- \ “Kissing a smoker is like licking an ashtray.” —anonymous | `\ | _o__) | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Life Grid Implementation
On 20/04/15 01:36, niy mor wrote: Is my code completing the assignment??? No. I need some *guidance* on completing my assignment. Try running your code. Then fix the errors. If you can't fix them come back to us and ask for help, including the error message and a description of what happened and what you expected. My Attempt Code: class SparseLifeGrid : Cell = ["row", "col"] What is this for? def __init__( self ): self._rowList = [] self._colList = [] self._cellSet = set() def _binarySearch( self, target ) : low = 0 high = len(self._cellSet - 1) while low <= high : mid = (high + low) // 2 if theList[mid] == target : return (True, mid) elif target < theList[mid] : high = mid - 1 else : low = mid + 1 return (False, low) This just tells you which half the item is in. Is that what you wanted? def minRange( self ): return (sorted(self._rowList)[0], sorted(self._rowList)[0]) This returns the same value twice. def maxRange( self ): return (sorted(self._rowList, reverse = True)[0],\ sorted(self._colList, reverse = True)[0]) You don;t need the line continuation character (/) if you are inside parens. def f(): return (expression1, expression2) # Clears the individual cell (row, col) and sets it to dead. If the cell is # already dead, no action is taken def clearCell( self, row, col ): for item in self : if item == Cell(row, col) : self.remove(item) How do you expect to iterate over self? self is your class instance but it has nothing to iterate over? def setCell( self, row, col ): LIVE_CELL = 1 Cell[row, col] = LIVE_CELL Here you create a new Cell instance then try to assign a value to it, then throw it away. I'm pretty sure thats not what you want. def isLiveCell( self, row, col): return Cell(row,col) in self Again how are you testing 'in' self. There is nothing in your class to support that. def numLiveNeighbors( self, row, col ): surround = 0 if self.isLiveCell(row + 1, col) : surround += 1 if self.isLiveCell(row - 1, col) : surround += 1 if self.isLiveCell(row, col + 1) : surround += 1 if self.isLiveCell(row, col - 1) : surround += 1 How many neighbours does a cell have in a Life grid? Is it only 4? -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
On 20/04/2015 04:49, Jim Mooney wrote: For randomly generating data which look like addresses, I use: http://www.generatedata.com/ While it has 'export to programming language' as a feature, Python isn't one of the supported languages. Which is fine. It can export into comma separated values, and writing a Python program to construct a dictionary from comma separated values is easy. Laura That's a great source, and I can generate dictionaries using the other advice. If you don't request comma delimited, each record per line has | as a field delimiter, so making big dicts was easy. Naturally, I tried emailing one of the addresses - aliq...@nunc.org - but it appears to be dead ;') Come to think of it, since I used | as a delimiter, what happens if you generate a CSV file from data that already has commas in the text? For those who don't know you can use any character as the delimiter and any character as the quote, see https://docs.python.org/3/library/csv.html#csv.reader -- My fellow Pythonistas, ask not what our language can do for you, ask what you can do for our language. Mark Lawrence ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How to close a Tkinter window from a different thread?
On Mon, Apr 20, 2015 at 2:10 AM, Alan Gauld wrote: > On 20/04/15 04:34, boB Stepp wrote: > >> So, how do I: >> 1) Check for the existence of an already open window from a previous >> running of the script? >> 2) If such a window exists, how do I close it from the new script >> execution? And, then, of course generate a new instance of the >> information window. > > > I would suggest forgetting about windows and think about > the processes that create them. Use the OS tools (via > the os module) to see if the first process is still running. > If so kill the process - which will in turn kill the window. I started poking around a little in this area in my books, but did not know if this was the way to go or not. I was still hung up on how to identify the correct process... > You can find the process based on its name or based on > its PID which you could store in a file somewhere > (like in /tmp?) I was thinking in these terms from a Tkinter window id perspective, but storing the PID while the original window is known to be open looks like the way to go. Thanks, Alan! I may have more questions on this later as I have not explicitly worked with this via Python. I've only killed processes via the command line before. >> I feel the solution must be in Tkinter's access to the X Window >> system, but nothing in the documentation is *clicking* with me yet. > > > Trying to manipulate GUIs via the windowing system should always > be a last resort, it is very hard to get right. If I am learning nothing else from my exploration of GUI programming, this is becoming ever more evident! -- boB ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] bin to dec conversion puzzlement
I can't seem to get my head around this 'simple' book example of binary-to-decimal conversion, which goes from left to right: B = '11011101' I = 0 while B: I = I * 2 + int(B[0]) B = B[1:] print(I) >>> 221 My thought was to go from right to left, multiplying digits by successive powers of two, and adding, like so: B = '11011101' sum = 0 for exp, num in enumerate(reversed(B)): sum += int(num) * 2**exp print(sum) >> 221 Both methods work but I just can't see how the first one does. Am I missing something obvious here? -- Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] How to close a Tkinter window from a different thread?
In a message of Mon, 20 Apr 2015 08:10:38 +0100, Alan Gauld writes: >Trying to manipulate GUIs via the windowing system should always >be a last resort, it is very hard to get right. And the hardness increases exponentially if you want to be portable across different operating systems. Laura ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
> Which is why you should use the csv module to work with csv files, > it knows how to deal with these various exceptional cases. > -- > Alan G > I should have known to simply try importing csv. Must-remember-batteries-included ;') -- Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] OT: Is there a good book that covers the history/evolution of software? [Inspired by the thread: lists, name semantics]
Newman, W., Sproull, R. (1979), Principles of Interactive Computer Graphics, Mcgraw-Hill College, ISBN 0-07-046338-7 is a very good read. It is understandably dated, but then it was history that you were looking for. And the book has 2 parts -- a history of the computer architectures we had (in 1979) and then the part on how to make grapical programs on them. Laura ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
In a message of Sun, 19 Apr 2015 20:49:27 -0700, Jim Mooney writes: >Come to think of it, since I used | as a delimiter, what happens if you >generate a CSV file from data that already has commas in the text? > >-- >Jim In Sweden, and lots of other places, we do numbers differently. This is One thousand dollars and 43 cents. 1.000,43 Lots of the time you write that as 1000,43 same as in English you get 1000.43 and 1,000.43. So we tend to use comma separated values around here that are really semi-colon separated values. But I do not know how widespread that usage is. Laura ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Life Grid Implementation
I don't understand how to do this. I attempted with my code and hoped a tutor could help me with this On Apr 20, 2015 3:31 AM, "Ben Finney" wrote: > niy mor writes: > > > Is my code completing the assignment??? > > Does it meet the requirements when you (and other people) run the code? > > > I need some *guidance* on completing my assignment. > > Can you be specific about what you don't understand? > > If you don't understand the requirements, that is best discussed with > your course supervisor, not us. > > -- > \ “Kissing a smoker is like licking an ashtray.” —anonymous | > `\ | > _o__) | > Ben Finney > > ___ > Tutor maillist - Tutor@python.org > To unsubscribe or change subscription options: > https://mail.python.org/mailman/listinfo/tutor > ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Please Help to build an addon for Anki
Hi
I liked the addon "Picture-flasher" written for anki very much
and I was wondering if the same thing could be done with mp3 and/or
flac files. Means I am looking for an addon that chooses a random mp3
and/or flac file from a directory provided by me (to the addon as we
have to provide in "Picture-flasher") and plays it on successful
reviewing of a certain number of cards (as does the addon
"Picture-flasher"). As a music lover, I feel that this addon can
motivate a whole lot of music lovers out there to pay a visit to Anki
on their PC and review to listen to their favorite mp3 and/or flac
files as a reward.
I am not a programmer yet, please guide.
Hoping for a quick response.
Mahesh Chirmure
# -*- coding: utf-8 -*-
# Picture-Flasher (a plugin for Anki)
# Authors:
# Emanuel Rylke, ema-...@web.de
# D_Malik, malik6...@gmail.com
# Version 2
# License: GNU GPL, version 3 or later; http://www.gnu.org/copyleft/gpl.html
"""
A simple plugin that flashes pictures on-screen to reinforce reviews.
Before using:
- Get pictures from someplace. I downloaded pictures off reddit using the
script at https://github.com/dpbrown/RedditImageGrab
- Change all lines (in the plugin source) marked with "CHANGEME" according to
your preferences.
For more details, see the post at For more details, see the post at
http://lesswrong.com/r/discussion/lw/frc/two_anki_plugins_to_reinforce_reviewing/
"""
from anki.hooks import addHook
from aqt import mw
from random import random, choice
from aqt.qt import QSplashScreen, QPixmap, QTimer
from os import listdir
#-- begin configuration --#
pictureDirectory = "E://Family stuff//22 Feb//Personal//College//A J//"
#CHANGEME to the directory where you're storing your pictures. NB: This MUST
end with a trailing slash e.g. D://Family stuff//19 Jan//Imgs//Wallys//,
D://Family stuff//22 Feb//Imgs//Windows 7//.
flashTime = 3000 #CHANGEME to change how long pictures stay on the screen. The
number is time in milliseconds.
#flashPosition = [20, 1050] #CHANGEME if you want the picture to be shown at a
specific location. The numbers are x- and y-coordinates.
#CHANGEME: The next lines are a python dictionary associating deck names
with probabilities of pictures being shown.
#Eg, when using the deck "brainscience", you will get a picture after 30%
of cards. When using a deck without a listed name, "other" is used.
#Change this according to your decks. Decks with shorter, easier cards need
lower probabilities.
deckPicsProbabilities = {
"rocketsurgery": 0.3,
"brainscience" : 0.5,
"other": 0.1,
}
#--- end configuration ---#
pics = listdir(pictureDirectory)
def showPics():
if mw.col.decks.current()['name'] in deckPicsProbabilities:
picsProbability = deckPicsProbabilities[mw.col.decks.current()['name']]
else:
picsProbability = deckPicsProbabilities["other"]
if random() < picsProbability:
mw.splash = QSplashScreen(QPixmap(pictureDirectory + choice(pics)))
try:
mw.splash.move(flashPosition[0], flashPosition[1])
except NameError:
pass
mw.splash.show()
QTimer.singleShot(flashTime, mw.splash.close)
addHook("showQuestion", showPics)
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Re: [Tutor] bin to dec conversion puzzlement
On Apr 20, 2015 6:56 AM, "Jim Mooney" wrote: > > I can't seem to get my head around this 'simple' book example of > binary-to-decimal conversion, which goes from left to right: > > B = '11011101' > I = 0 > while B: > I = I * 2 + int(B[0]) > B = B[1:] > > print(I) > >>> 221 > > My thought was to go from right to left, multiplying digits by successive > powers of two, and adding, like so: > > B = '11011101' > sum = 0 > > for exp, num in enumerate(reversed(B)): > sum += int(num) * 2**exp > > print(sum) > >> 221 > > Both methods work but I just can't see how the first one does. Am I missing > something obvious Start from 0. As long as there are any digits left, a) Multiply by 2, add the leftmost digit. b) Chop off the leftmost digit. Lather, rinse, repeat. It _does_ seem counterintuitive to do it from the left, but it's actually quite simple. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
On 20 April 2015 at 08:44, Jim Mooney wrote: > I can't seem to get my head around this 'simple' book example of > binary-to-decimal conversion, which goes from left to right: > > B = '11011101' > I = 0 > while B: > I = I * 2 + int(B[0]) > B = B[1:] Follow through the loop and see what happens. To begin I is zero and B is the full string. Consider B_orig to be the original string. After the first iteration we have that I = B[0] and B = B_orig[1:] then I = 2*B[0] + B[1] and B = B_orig[2:] then I = 2*(2*B[0] + B[1]) + B[2] = 4*B[0] + 2*B[1] + B[2] then I = 8*B[0] + 4*B[1] + 2*B[2] + B[3] and eventually I = 128*B[0] + 64*B[1] + ... + 2*B[6] + B[7] which is the desired result. Oscar ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] introspection
Does python provide the introspective ability to retrieve the name to
which an object is bound?
For example:
$ python3
Python 3.4.0 (default, Apr 11 2014, 13:05:18)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
a = 69
print("Identifier <{}> is bound to {}.".format(a.__name__, a))
Traceback (most recent call last):
File "", line 1, in
AttributeError: 'int' object has no attribute '__name__'
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Re: [Tutor] introspection
On Mon, Apr 20, 2015 at 11:24 AM, Alex Kleider wrote:
> Does python provide the introspective ability to retrieve the name to which
> an object is bound?
>
> For example:
> $ python3
> Python 3.4.0 (default, Apr 11 2014, 13:05:18)
> [GCC 4.8.2] on linux
> Type "help", "copyright", "credits" or "license" for more information.
a = 69
print("Identifier <{}> is bound to {}.".format(a.__name__, a))
>
> Traceback (most recent call last):
> File "", line 1, in
> AttributeError: 'int' object has no attribute '__name__'
>
>
An object can be bound to multiple names. Within a namespace you can
use locals to see names, then compare various names like so:
>
>>> a = 3
>>> b = 6
>>> c = a
>>> locals()
{'a': 3, 'c': 3, 'b': 6, '__builtins__': , '__package__': None, '__name__': '__main__', '__doc__':
None}
>>> a is b
False
>>> a is c
True
>>>
>
>
> ___
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--
Joel Goldstick
http://joelgoldstick.com
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Re: [Tutor] Life Grid Implementation
On 20/04/15 13:59, niyana morgan wrote: I don't understand how to do this. I attempted with my code and hoped a tutor could help me with this Always write code that runs. Then fix the mistakes as they happen. That way you only have a few lines of code to look at. Your code is far too big and intertwined to be able to debug easily. Look at your specification: • SparseLifeGrid() Creates a new infinite-sized game grid with all cells initially dead. ... • clearCell(row, col) Clears the individual cell (row, col) and sets it to dead. If the cell is already dead, no action is taken. • setCell(row, col) Sets the indicated cell (row, col) to be alive. If the cell is already alive, no action is taken. I suggest you start over with a class definition and an init(). See if you can create an instance and if it has the fields you expect. Thats your first API bullet done. Once you can do that create the methods needed to populate it with data (setCell()) and clear a cell(clearCell()). Nothing else, just those two methods. Get them working. Now you have three parts of your assignment done. Only when you can do those things correctly attempt one of the remaining API methods - maybe the isLiveCell() method. Then try minRange and maxRange after that. Finally you can try numLiveNeighbours confident that the rest of the class works. Always run the code. Every time you complete a method your code should work. If you write your tests as code in a function, that function should always work even after you complete a new stage. If anything that used to work stops working, go back and fix it before trying anything new. The code you changed will still be fresh in your mind. If you really get stuck come back here and ask. Always copy any error messages in full. HTH -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
On 20/04/15 08:44, Jim Mooney wrote: I can't seem to get my head around this 'simple' book example of binary-to-decimal conversion, which goes from left to right: B = '11011101' I = 0 while B: I = I * 2 + int(B[0]) B = B[1:] ... Both methods work but I just can't see how the first one does. The key is that the result gets multiplied by 2 each time so for an N bit number the leftmost digit winds up being effectively 2**N, which is what you want. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Please Help to build an addon for Anki
On 20/04/15 09:54, Mahesh Chiramure wrote: I liked the addon "Picture-flasher" written for anki very much and I was wondering if the same thing could be done with mp3 and/or flac files. Probably, but I (and probably most of the list) have no idea what anki is or what the addon does. This is a list for learning Python and its standard library. You could try asking on the general Python mailinglist/newsgroup where you might find someone familiar with it. If you do try that you sould try explaining what anki is, and what the addon does. ie how it 'adds on'. Better still is if you can find an anki forum, since they will understand anki, addons and probably be familiar with the PictureFlasher one you describe. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
On 2015-04-20 09:15, Joel Goldstick wrote:
On Mon, Apr 20, 2015 at 11:24 AM, Alex Kleider
wrote:
Does python provide the introspective ability to retrieve the name to
which
an object is bound?
For example:
$ python3
Python 3.4.0 (default, Apr 11 2014, 13:05:18)
[GCC 4.8.2] on linux
Type "help", "copyright", "credits" or "license" for more information.
a = 69
print("Identifier <{}> is bound to {}.".format(a.__name__, a))
Traceback (most recent call last):
File "", line 1, in
AttributeError: 'int' object has no attribute '__name__'
An object can be bound to multiple names. Within a namespace you can
use locals to see names, then compare various names like so:
a = 3
b = 6
c = a
locals()
{'a': 3, 'c': 3, 'b': 6, '__builtins__': , '__package__': None, '__name__': '__main__', '__doc__':
None}
a is b
False
a is c
True
Showing my desired use case might make my question more understandable:
def debug(var_name):
if args["--debug"]:
print("Identifier <{}> is bound to: {}"
.format(var_name.__name__, repr(var_name)))
I don't think the built in locals() can help me.
Thanks all the same.
Alex
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Re: [Tutor] bin to dec conversion puzzlement
On 2015-04-20 09:21, Alan Gauld wrote: On 20/04/15 08:44, Jim Mooney wrote: I can't seem to get my head around this 'simple' book example of binary-to-decimal conversion, which goes from left to right: B = '11011101' I = 0 while B: I = I * 2 + int(B[0]) B = B[1:] ... Both methods work but I just can't see how the first one does. The key is that the result gets multiplied by 2 each time so for an N bit number the leftmost digit winds up being effectively 2**N, which is what you want. Shouldn't that be 2**(N-1)? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
On Mon, Apr 20, 2015 at 11:21 AM, Alan Gauld wrote: >> >> B = '11011101' >> I = 0 >> while B: >> I = I * 2 + int(B[0]) >> B = B[1:] > >> Both methods work but I just can't see how the first one does. > > The key is that the result gets multiplied by 2 each time > so for an N bit number the leftmost digit winds up being > effectively 2**N, which is what you want. The loop iterates N times, so the leftmost digit is multiplied by 2 a total of N - 1 times, i.e. B[0] * 2 ** (N - 1). Another way to see this is that multiplying by 2 is a bitwise left shift. Thus you can replace the multiplication and addition with bitwise operations as follows: B = '11011101' I = 0 while B: I = (I << 1) | int(B[0], 2) B = B[1:] assert I == 221 Shifting the values in like this may be more intuitively obvious. ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
On 20/04/15 17:58, Alex Kleider wrote: The key is that the result gets multiplied by 2 each time so for an N bit number the leftmost digit winds up being effectively 2**N, which is what you want. Shouldn't that be 2**(N-1)? Yes, sorry. -- Alan G Author of the Learn to Program web site http://www.alan-g.me.uk/ http://www.amazon.com/author/alan_gauld Follow my photo-blog on Flickr at: http://www.flickr.com/photos/alangauldphotos ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
On Mon, Apr 20, 2015 at 08:24:42AM -0700, Alex Kleider wrote: > Does python provide the introspective ability to retrieve the name to > which an object is bound? Short answer: no. Slightly longer answer: it *may* be possible if you dig deep into the debugger API that you might find something which does what you want. I'm not saying that it will, only that if it exists, the debugger seems like the most likely place. But... probably not. In any case, even if you find something that will do this, it will be implementation-specific (e.g. Jython only, or IronPython only, or CPython only, but not all three) and probably rather dubious. After all, any object may have zero, one or more names, in completely different scopes. The whole idea of "what name does this object have" is rather dubious. The best one can do is say "in this namespace (locals), does this object have any names?". -- Steve ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
On 20/04/15 17:55, Alex Kleider wrote:
locals()
{'a': 3, 'c': 3, 'b': 6, '__builtins__': , '__package__': None, '__name__': '__main__', '__doc__':
None}
Showing my desired use case might make my question more understandable:
def debug(var_name):
if args["--debug"]:
print("Identifier <{}> is bound to: {}"
.format(var_name.__name__, repr(var_name)))
I don't think the built in locals() can help me.
Why not? Provided you pass the required scope into your function:
def debug(var_name, scope):
if args["--debug"]:
print("Identifier <{}> is bound to: {}"
.format(var_name, scope.get(var_name, 'no object'))
debug('a',locals()) # look in local vars
--
Alan G
Author of the Learn to Program web site
http://www.alan-g.me.uk/
http://www.amazon.com/author/alan_gauld
Follow my photo-blog on Flickr at:
http://www.flickr.com/photos/alangauldphotos
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Re: [Tutor] introspection
Alex Kleider wrote:
> On 2015-04-20 09:15, Joel Goldstick wrote:
>> On Mon, Apr 20, 2015 at 11:24 AM, Alex Kleider
>> wrote:
>>> Does python provide the introspective ability to retrieve the name to
>>> which
>>> an object is bound?
>>>
>>> For example:
>>> $ python3
>>> Python 3.4.0 (default, Apr 11 2014, 13:05:18)
>>> [GCC 4.8.2] on linux
>>> Type "help", "copyright", "credits" or "license" for more information.
>>
>> a = 69
>> print("Identifier <{}> is bound to {}.".format(a.__name__, a))
>>>
>>> Traceback (most recent call last):
>>> File "", line 1, in
>>> AttributeError: 'int' object has no attribute '__name__'
>>>
>>>
>> An object can be bound to multiple names. Within a namespace you can
>> use locals to see names, then compare various names like so:
>>>
> a = 3
> b = 6
> c = a
> locals()
>> {'a': 3, 'c': 3, 'b': 6, '__builtins__': > (built-in)>, '__package__': None, '__name__': '__main__', '__doc__':
>> None}
> a is b
>> False
> a is c
>> True
>
> Showing my desired use case might make my question more understandable:
> def debug(var_name):
> if args["--debug"]:
> print("Identifier <{}> is bound to: {}"
> .format(var_name.__name__, repr(var_name)))
> I don't think the built in locals() can help me.
> Thanks all the same.
> Alex
In CPython you can inspect the callstack, but remember that
(1) it is a costly operation
(2) there are many variables bound to multiple names or none at all.
$ cat show_name_binding2.py
import sys
def bindings_of(value, depth):
frame = sys._getframe(depth + 1)
bindings = [n for n, v in frame.f_locals.items() if v is value]
if bindings:
return bindings
return [""]
def debug(value):
print("{} is bound to {}".format(
value, ", ".join(bindings_of(value, 1
def main():
x = 42
y = 42
debug(42)
debug("foo")
a = "bar baz"
b = " ".join(a.split())
assert a == b
debug("bar baz")
if __name__ == "__main__":
main()
$ python3 show_name_binding2.py
42 is bound to y, x
foo is bound to
bar baz is bound to a
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[Tutor] Is it possible to "backport" the datetime module of Python 3.3 to Python 3.2?
Hi, My Raspberry Pi 2 comes with Python 3.2 (and 2.7). I run some code that uses the datetime module but I get an error: "AttributeError: 'datetime.datetime' object has no attribute 'timestamp'". On https://docs.python.org/3/whatsnew/3.3.html I see: "New datetime.datetime.timestamp() method: Return POSIX timestamp corresponding to thedatetime instance." Is upgrading Python 3.3 or higher my only option, or is it somehow possible to use the newer version of the datetime library for Python 3.2? I do not want to modify the source code of the library that causes the error (pysolar). Thanks! Regards, Albert-Jan ~~ All right, but apart from the sanitation, the medicine, education, wine, public order, irrigation, roads, a fresh water system, and public health, what have the Romans ever done for us? ~~ ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] sample dictionairies
Jim Mooney writes: > I should have known to simply try importing csv. Better: You should now know to refer to the documentation https://docs.python.org/3/library/>. -- \ “Speech is conveniently located midway between thought and | `\action, where it often substitutes for both.” —John Andrew | _o__) Holmes, _Wisdom in Small Doses_ | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
Alex Kleider writes: > Does python provide the introspective ability to retrieve the name to > which an object is bound? Objects aren't bound to names. So, no. The binding from a reference (a name is a reference) to objects is one-way. See this excellent presentation from PyCon US 2015 by Ned Batchelder https://www.youtube.com/watch?v=_AEJHKGk9ns>. -- \ “I must say that I find television very educational. The minute | `\ somebody turns it on, I go to the library and read a book.” | _o__)—Groucho Marx | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
Jim Mooney writes: > I can't seem to get my head around this 'simple' book example of > binary-to-decimal conversion, which goes from left to right: > > B = '11011101' > I = 0 > while B: > I = I * 2 + int(B[0]) > B = B[1:] > > print(I) > >>> 221 That is, IMO, a needlessly confusing way to write that code. Whoever wrote it is clearly pleased with how clever it is; but cleverness is almost always a property of *bad* code because it's difficult to understand at a glance. That's the case here. One significant problem with the code as written is that it uses a ‘while’ loop and mutates the list, where there's no point; it should just iterate over items *from* the list without changing it. Another significant problem is that it uses moronically-short, completely unexpressive names. This is Python not FORTRAN. Try this:: binary_text = '11011101' result = 0 for binary_digit in binary_text: # Accumulate powers of 2 for each digit. result = result * 2 + int(binary_digit) print(result) > Both methods work but I just can't see how the first one does. Am I > missing something obvious here? No, you were missing something needlessly obscured by the badly-written code. Which book is this? I will be sure never to recommend it. Hope that helps. -- \ “Science is a way of trying not to fool yourself. The first | `\ principle is that you must not fool yourself, and you are the | _o__) easiest person to fool.” —Richard P. Feynman, 1964 | Ben Finney ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
The key is that the result gets multiplied by 2 each time > so for an N bit number the leftmost digit winds up being > effectively 2**N, which is what you want. > > Alan G Ah, the light dawns once it was restated. It would be even simpler if you could multiply each element of the binary number by it's respective power of two, and sum them all at once. I hear Py 3.5 will have vector abilities. I wonder it if would do something like that. Jim ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] bin to dec conversion puzzlement
On 04/20/2015 04:15 PM, Jim Mooney wrote:
The key is that the result gets multiplied by 2 each time
so for an N bit number the leftmost digit winds up being
effectively 2**N, which is what you want.
Alan G
Ah, the light dawns once it was restated. It would be even simpler if you
could multiply each element of the binary number by it's respective power
of two, and sum them all at once. I hear Py 3.5 will have vector abilities.
I wonder it if would do something like that.
It's important to understand these conversion methods, or I would have
earlier mentioned that you can convert from a binary string simply by
x = int("1011", 2)
No loop needed.
But if you need a loop for an analagous algorithm, find a way to either
minimize the number of times through the loop, or to reduce the work
done in each loop.
Ben's algorithm is much simpler than the one in the book you're reading.
binary_text = '11011101'
result = 0
for binary_digit in binary_text:
# Accumulate powers of 2 for each digit.
result = result * 2 + int(binary_digit)
print(result)
But more importantly, it's much simpler than calculating various powers
of two and multiplying the various coefficients by them, and somehow
"sum them all at once".
--
DaveA
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Re: [Tutor] How to close a Tkinter window from a different thread?
On Mon, Apr 20, 2015 at 2:10 AM, Alan Gauld wrote: > On 20/04/15 04:34, boB Stepp wrote: > >> So, how do I: >> 1) Check for the existence of an already open window from a previous >> running of the script? >> 2) If such a window exists, how do I close it from the new script >> execution? And, then, of course generate a new instance of the >> information window. > > > I would suggest forgetting about windows and think about > the processes that create them. Use the OS tools (via > the os module) to see if the first process is still running. > If so kill the process - which will in turn kill the window. > > You can find the process based on its name or based on > its PID which you could store in a file somewhere > (like in /tmp?) I'm currently at home and cannot access Solaris, but I believe that the following will do what I want: import os import signal from tkinter import * def kill(): os.kill(pid, signal.SIGKILL) root = Tk() pid = os.getpid() btn = Button(root, text='Kill me!!!', command=kill) btn.pack() root.mainloop() The process id would have to be stored persistently to do the real deal, of course, as Alan suggested. I cannot make this example work in Windows. As far as I can tell, signal.SIGKILL won't work with Windows. If I replace it with 9, then it does work. If I have understood what I have read to date, using signal.SIGKILL is preferable to using 9. Some questions: 1) Is the placement of "pid = os.getpid()" critical? My thinking is that I want to capture the pid of the root window, store it, and then use it if I need to kill the root and any children it has in my actual GUI display. If, say, I placed it immediately before "root.mainloop()", would it do what I want? Of course, I plan to experiment with this at work tomorrow. I'll also continue to play around with it in Windows. 2) The other possibility was to use "os.getppid" and, I suppose, "os.kill(ppid, signal.SIGKILL)". Would this be preferable? Or will wreak some sort of havoc? Thanks! boB ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
On 2015-04-20 13:24, Ben Finney wrote: Alex Kleider writes: Does python provide the introspective ability to retrieve the name to which an object is bound? Objects aren't bound to names. So, no. The binding from a reference (a name is a reference) to objects is one-way. See this excellent presentation from PyCon US 2015 by Ned Batchelder https://www.youtube.com/watch?v=_AEJHKGk9ns>. But my code knows the name. The code is provided the name; I want the code to tell me that name. ..but it seems unable to do so. ;-( ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] introspection
What's supposed to happen in this situation? ## class Person(object): def __init__(self): pass j = Person() john = j jack = j ## What single name should we get back from the single Person object here? "j", "john", or "jack"? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
