Re: [Tutor] Help Please
Mario,
On 21/02/19 3:30 AM, Mario Ontiveros wrote:
Hello,
I am new to python and have been stuck on this for a while. What I am
trying to do is to remove rows with void, disconnected, and error on lines. The
code I have does that, the only problem is that it removes my header because
void is in header. I need to keep header.
with open("PSS.csv","r+") as f:
new_f = f.readlines()
f.seek(0)
for line in new_f:
if "Void" not in line:
if "Disconnected" not in line:
if "Error" not in line:
f.write(line)
f.truncate()
Would it be 'safer' to create a separate output file?
Rather than reading the entire file (easily managed if short, but
unwieldy and RAM-hungry if thousands of records!), consider that a file
object is an iterable and process it one line/record at a time.
with open( ... ) as f:
header = f.readline()
# deal with the header record
for record in f:
function_keep_or_discard( record )
#etc
In case it helps you to follow the above, and possibly to learn other
applications of this thinking, herewith:-
An iterable matches a for-each-loop very neatly (by design). It consists
of two aspects: next() ie give me the next value (thus for each value in
turn), and the StopIteration exception (when next() asks for another
value after they have all been processed). The for 'swallows' the
exception because it is expected. Hence, you don't need to try...except!
Something a lot of pythonistas don't stop to consider, is that once code
starts iterating an object, the iteration does not 'reset' until
"exhausted" (unlike your use of f.seek(0) against the output file).
Accordingly, we can use a 'bare' next() to pick-out the first (header)
record and then pass the rest of the job (all the other next()s) to a
for-each-loop:
with open( ... ) as f:
header = next( f ) # grab the first record
# deal with the header record
for record in f:# iterate through the remaining records
#etc
--
Regards =dn
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Re: [Tutor] LPTHW ex15 question
Kayla, On 22/03/19 1:43 AM, Jones, Kayla wrote: I am working through excersise 15 of LPTHW and am getting an error message in powershell that I can't figure out. I've attached a screenshot to help. Any suggestions would be appreciated. Attachments don't seem to work on the mailing list. Plus, if you copy-paste code (and errmsgs) then we can do the same! (to reproduce the problem/save time coding a fix) -- Regards =dn ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] cant get it to run right
On 29/03/19 12:55 PM, Sveum, Christian wrote:
I am new and I have tried everything I can think I of. I want it to run like a
converstion.
print(" I am Bob")
...
What is not working?
How far does the program run before stopping?
What error message are you seeing?
(why won't you share it with us?)
--
Regards =dn
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Re: [Tutor] Looking for some direction
Cranky, It is a little difficult to answer your question. First impression is that your experience gives you good ideas of how to solve the problem. Some of them may not suit the Python environment as well as (say) that of PHP/MSFT. So, a learning opportunity there too. Second impression is that there are a lot of moving parts. How many of them do you know well, and how many are learning-targets? Trying to tackle 'too much' that is 'new' may result in heavy frustration. (no mention of skill-levels, so 'just sayin') The web-ref is not a book, but a *simple* article. It will serve, as long as you stick within the narrow scope of that article. The instant you deviate or customise, you're 'on your own'. For this reason, my recommendation is always a (proper/full) book*, if at all possible. You speak of MVC, so one (of many) Python web framework is Mig Grinberg's "Flask". Apart from his own, there are several other books which cover this subject. Following such a text will enable you to start-out on 'toy examples' and then gather expertise. Likely, you will re-shape this project whilst learning. * I used the term "book" but the last person to whom I recommended such couldn't afford the cost, and these days there are many excellent on-line and equally structured alternatives, eg Python courses on Coursera.org and edX.org (both 'freemium' offerings) - IIRC(?) Flask is available on Lynda (LinkedIN). That said, let's try responding to each of your points:- On 12/05/19 6:59 AM, Cranky Frankie wrote: I'm a long time IT professional trying to teach myself object-oriented programming. As such I want to build a traditional PC app using MVC (Model - View - Controller) architecture. Just want to make sure I'm heading about this in the best way so I'm looking for some direction. For the Model or persistence layer I want to use SQLite. For the View or GUI I want to use wxPython. For the Controller I want to of course use Python. I'm also planning on using Git for source control. 1) For the IDE I'm most comfortable with Netbeans/Java, but I'm forcing myself to try and get comfortable with PyCharm. Is it worth sticking it out with PyCharm, or should I go with the Python module in Netbeans? Or is there another IDE I should look at? To my observation an IDE is less important in Python (than for highly structured, strongly typed, compiled, ... languages). My advice is, once you've chosen and found that it works, do NOT switch editor/IDE in anything less than one year. Under the 80-20 'rule', we use a basic few editing 'features' to do most of our work. Thus, it stands to reason that it will take periods of 'real time' before you decide 'there must be an easier way' to achieve some functionality and go looking in the editor's menus/help/etc to see if/what it might be! The other aspect is that 'religious wars' are fought over "which is the best editor/IDE" style questions. If you believe 'everyone' you'll 'jump' so often that you'll never figure-out 'which'. So, given that PyCharm is purpose-built, has a good reputation, and you have already used it: "if it ain't broke, why fix it"? (NB I don't use it, but have in the past) 2) For wxPython I'm finding a lot of the documentation is outdated. Is this book any good: http://www.blog.pythonlibrary.org/2019/05/08/creating-gui-applications-with-wxpython-now-available/ Or is there a better book/course/website I should be working with? Or is there a better grahpics framework at this point for a traditional desktop app? - attempted to tackle in 'strategy' comments, above 3) For the O-O part, I'm comfortable with Inheritance and Composition. Do I need to worry about any of the more advanced design patterns? This app will be for vehicle ownership - tracking maintenance, etc. Nothing fancy. At risk of creating a dichotomy, whilst there are books which attempt to 'translate' the original gang-of-four patterns (and more) into 'Python', none has really impressed. "Pythonista" talk of "pythonic" solutions. Personal observations when learning Python (as if I'm not still...) included the need to desist from trying to solve a problem in xyz-other-language and 'translate' that to Python, but to learn how Python's construction enables its own solution-approach - sometimes quite distinctive. My favorite simple example of this is that many other languages offer do/for-loops. However Python's construct should be called for-each because it does not manage an index, eg loop-around doing something with array[index]; but instead/additionally "iterates" over a "collection", eg for item in list: ... Which also disposes of the need to learn the GoF iterator pattern as a "pattern" - but does not excuse you from understanding the "idiom". Once again, such are best (IMHO) learned from the cohesive and comprehensive coverage of a decent Python book*, cf numerous and unrelated web/blog/etc entries. 4) I plan to write my Use Case in Libre
Re: [Tutor] Two Scripts, Same Commands, One Works, One Doesn't
Stephen, On 16/05/19 12:16 AM, Stephen P. Molnar wrote: I am writing scripts to semi-automate some of my Quantum Chemistry software and have encountered a problem that has me baffled. The two scripts have the same form, the only difference being the commands. One script works, the other bombs. Blast from the past! I thought I'd finished with nerve agents, receptors, and ligands back in 1990-1. The memories have not improved with age! Taking the first question, ie 'two scripts which appear identical but are not':- Nothing 'popped' during a quick visual scan. Linux (which it is assumed you are using) has two basic built-in commands/pgms: diff and cmp (difference and compare). For occasions when I want to compare directories first, and probably contained-files thereafter, I use "Meld". As to the second: +1 to removing the extra moving-parts, like Spyder, and running directly from the cmdLN (simplify, simplify). Even though accuracy and precision are important, this is the Tutor list, so don't worry too much about the terminology. Most of us, young or old will have recognised what you meant. Whilst I can't recall the last time I used the term "bomb", I'm guessing that "abend" wouldn't pass muster either... -- Regards =dn ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Looking for some direction
On 13/05/19 10:56 AM, boB Stepp wrote: On Sun, May 12, 2019 at 5:19 PM boB Stepp wrote: On Sun, May 12, 2019 at 1:05 PM David L Neil wrote: I'm using Gnome Terminal under Fedora (Linux). This allows multiple terminals in tabs (and thus Ctrl-Tab rapid-switching). However, it irritates me that whilst I can set "profiles" for particular purposes; there does not seem to be a way to save a 'session'. Thus each time Terminal re-starts, I have to re-build each terminal, manually. (suggestions of other similar tools would be most welcome) I may be mistaken, but I think that a terminal multiplexer like tmux (https://github.com/tmux/tmux/wiki) is capable of session management. I have no personal use of tmux, but have been intrigued enough about others referring to it that eventually I will get around to seriously checking it out. Actually, tmux is starting to look more and more interesting. David, I think you might this helpful. I am currently looking at an introduction to tmux by a Stack Overflow developer. This article is at https://www.hamvocke.com/blog/a-quick-and-easy-guide-to-tmux/ (There was a link to this on the tmux wiki I sent out a link to earlier.) I think I may start playing around with this! Thanks Bob. Am taking it for a spin... -- Regards =dn ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Multiprocessing with many input input parameters
Sydney, 1 There have been many projects to look at cells, division, multiplication, ... It is worth researching the Python eco-system in the expectation of saving yourself time and effort! 2 The latest releases of Python (such as you quote) offer updated asyncio module(s) for multiprocessing, ie be careful if you are reading older articles! We haven't discussed hardware. Most modern PC CPUs offer multiple "cores". Assuming (say) four cores, asyncio is capable of running up to four processes concurrently - realising attendant acceleration of the entirety. (admittedly, I tend to limit my ambitions to number_of_cores - 1) On 12/07/19 3:40 AM, Mike Barnett wrote: If you're passing parameters as a list, then you need a "," at the end of the items. Otherwise if you have something like a string as the only item, the list will be the string. list_with_one_item = ['item one',] @mike -Original Message- From: Shall, Sydney Sent: Wednesday, July 10, 2019 11:44 AM To: tutor@python.org Subject: [Tutor] Multiprocessing with many input input parameters I am using MAC OS X 10.14.5 on a MAC iBook I use Python 3.7.0 from Anaconda, with Spyder 3.3.3 I am a relative beginner. My program models cell reproduction. I have written a program that models this and it works. Now I want to model a tissue with several types of cells. I did this by simply rerunning the program with different inputs (cell characteristics). But now I want to send and receive signals between the cells in each population. This requires some sort of concurrent processing with halts at appropriate points to pass and receive signals. I thought to use multiprocessing. I have read the documentation and reproduced the models in the docs. But I cannot figure out how to feed in the data for multiple parameters. I have tried using Pool and it works fine, but I can only get it to accept 1 input parameter, although multiple data inputs with one parameter works nicely. So, my questions are; 1. Is multiprocessing the suitable choice. 2. if yes, how does one write a function with multiple input parameters. Thank s in advance. Sydney Prodessor. Sydney Shall Department of Haematological Medicine King's College London 123 Coldharbour Lane London SE5 9NU ENGLAND E-Mail: sydney.shall (Correspondents outside the College should add @KCL.AC.UK) TEL: +44 (0)208 48 59 01 ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor -- Regards =dn ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
