[Tutor] Only appending one object to list, when I am expecting more than 1
I'm creating lots of objects from json in a file. Part of reading the json
back means that it iterates over the file and loads a json object and then
creates the object from the dictionary.
This is my file:
{"name": "Dwarf Fortress", "platform": "steam", "dateAdded":
"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756942"}
{"name": "Jaws", "platform": "Netflix", "dateAdded":
"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756960"}
{"name": "Wargames", "platform": "CLI", "dateAdded":
"2019:02:25:16:59:1551113984", "tpe": "Game"}
and these are the functions that help load that file:
media = []
def loadFile():
filename = input('Filename? ')
f = open(filename, 'r')
createObjects(f)
def createObjects(f):
'''Takes a file object and iterates through entries, passing them to
create
object, depending on what object it is.'''
for line in f:
count = count + 1
data = json.loads(line)
print(type(data['tpe']))
name = data['name']
platform = data['platform']
dateAdded = data['dateAdded']
tpe = data['tpe']
if data['tpe'] == 'Game':
a = createGame(name, platform, dateAdded,tpe)
game = {a: tpe}
media.append(game)
if data['tpe'] == 'Film':
a = createFilm(name, platform, dateAdded,tpe)
film = {a: tpe}
media.append(film)
# For some reason I'm only getting one object at a time now when
appending to media
print(len(media))
def createGame(name, platform, dateAdded, tpe):
return Game(name, platform, dateAdded)
def createFilm(name, platform, dateAdded, tpe):
return Film(name, platform, dateAdded)
(This isn't the order that the functions are held in the module).
Why would I only get one object in media, even though all three are created?
Adam
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Re: [Tutor] Only appending one object to list, when I am expecting more than 1
On Tue, Feb 26, 2019 at 09:09:56AM +, AdamC wrote: > def createObjects(f): > '''Takes a file object and iterates through entries, passing them to > create > object, depending on what object it is.''' > for line in f: > count = count + 1 This cannot be the code you are actually using, because that raises UnboundLocalError. count is never initialised, so that function you give cannot possibly run as shown. py> def test(): ... count = count + 1 ... py> test() Traceback (most recent call last): File "", line 1, in File "", line 2, in test UnboundLocalError: local variable 'count' referenced before assignment There's no point us trying to debug code you aren't actually running. Try again with the actual working code. It might help if you read this: http://www.sscce.org/ -- Steven ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
Re: [Tutor] Only appending one object to list, when I am expecting more than 1
AdamC wrote:
> I'm creating lots of objects from json in a file. Part of reading the json
> back means that it iterates over the file and loads a json object and then
> creates the object from the dictionary.
>
> This is my file:
>
> {"name": "Dwarf Fortress", "platform": "steam", "dateAdded":
> "2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756942"}
> {"name": "Jaws", "platform": "Netflix", "dateAdded":
> "2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756960"}
> {"name": "Wargames", "platform": "CLI", "dateAdded":
> "2019:02:25:16:59:1551113984", "tpe": "Game"}
>
> and these are the functions that help load that file:
>
> media = []
>
> def loadFile():
> filename = input('Filename? ')
> f = open(filename, 'r')
> createObjects(f)
>
> def createObjects(f):
> '''Takes a file object and iterates through entries, passing them to
> create
> object, depending on what object it is.'''
> for line in f:
> count = count + 1
> data = json.loads(line)
> print(type(data['tpe']))
> name = data['name']
> platform = data['platform']
> dateAdded = data['dateAdded']
> tpe = data['tpe']
> if data['tpe'] == 'Game':
> a = createGame(name, platform, dateAdded,tpe)
> game = {a: tpe}
> media.append(game)
> if data['tpe'] == 'Film':
> a = createFilm(name, platform, dateAdded,tpe)
> film = {a: tpe}
> media.append(film)
> # For some reason I'm only getting one object at a time now when
> appending to media
> print(len(media))
>
> def createGame(name, platform, dateAdded, tpe):
> return Game(name, platform, dateAdded)
>
> def createFilm(name, platform, dateAdded, tpe):
> return Film(name, platform, dateAdded)
>
> (This isn't the order that the functions are held in the module).
> Why would I only get one object in media, even though all three are
> created?
Only one record in your jsonl sample has a 'tpe' handled by createObjects().
To make it easier to catch this problem (invalid or unsuspected data) I
suggest that you rewrite the
> if data['tpe'] == 'Game':
> a = createGame(name, platform, dateAdded,tpe)
> game = {a: tpe}
> media.append(game)
> if data['tpe'] == 'Film':
> a = createFilm(name, platform, dateAdded,tpe)
> film = {a: tpe}
> media.append(film)
part of your code as
if data['tpe'] == 'Game':
a = createGame(name, platform, dateAdded,tpe)
game = {a: tpe}
media.append(game)
elif data['tpe'] == 'Film':
a = createFilm(name, platform, dateAdded,tpe)
film = {a: tpe}
media.append(film)
else:
# Instead of the error message you may also raise an exception.
print(
"Warning: unknown tpe={!r}".format(data["tpe"]),
file=sys.stderr
)
The unconditional else allows you to ensure that every line will be handled.
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Re: [Tutor] Only appending one object to list, when I am expecting more than 1
Thank you for a well formed problem description.
However, as Steven has remarked the code you've included doesn't run.
Can you follow up/reply with your actual working script, and also
include some of the output you get.
That said, I've a few small remarks about the code you have posted:
On 26Feb2019 09:09, AdamC wrote:
I'm creating lots of objects from json in a file. Part of reading the json
back means that it iterates over the file and loads a json object and then
creates the object from the dictionary.
This is my file:
{"name": "Dwarf Fortress", "platform": "steam", "dateAdded":
"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756942"}
{"name": "Jaws", "platform": "Netflix", "dateAdded":
"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756960"}
{"name": "Wargames", "platform": "CLI", "dateAdded":
"2019:02:25:16:59:1551113984", "tpe": "Game"}
BTW, I notice that only one of these rows has the "tpe" field set to
"Game" or "Film", specificly the last one. So based on your code below,
only one of these rows gets appended to the media array. Remarks below
on writing code which is less prone to hiding this kind of problem.
and these are the functions that help load that file:
media = []
def loadFile():
filename = input('Filename? ')
f = open(filename, 'r')
createObjects(f)
This f=open code would normally be written like this:
with open(filename, 'r') as f:
createObjects(f)
That construction ensures that the file gets closed after running
"createObjects()". As it is in your code the file is not explicitly
closed; the CPython interpreter will, as it happens, close the file
pretty promptly when "f" goes out of scope, but the language definition
doesn't require such immediacy.
def createObjects(f):
'''Takes a file object and iterates through entries, passing them to
create
object, depending on what object it is.'''
for line in f:
count = count + 1
data = json.loads(line)
print(type(data['tpe']))
name = data['name']
platform = data['platform']
dateAdded = data['dateAdded']
tpe = data['tpe']
if data['tpe'] == 'Game':
a = createGame(name, platform, dateAdded,tpe)
game = {a: tpe}
media.append(game)
if data['tpe'] == 'Film':
a = createFilm(name, platform, dateAdded,tpe)
film = {a: tpe}
media.append(film)
These if statements don't cover the case when "tpe" isn't "Game" or
"Film", and (in other circumstances) could conceivably add two objects.
If you construct it like this instead:
if data['tpe'] == 'Game':
a = createGame(name, platform, dateAdded,tpe)
game = {a: tpe}
media.append(game)
elif data['tpe'] == 'Film':
a = createFilm(name, platform, dateAdded,tpe)
film = {a: tpe}
media.append(film)
else:
print("Unhandled tpe value:", repr(tpe))
then (a) only 1 branch can ever apply and (b) reports any unexpected
values which would otherwise _silently_ get ignored. By always having a
final "else" in an if/elif//else chain you can catch/observe these
unhandled situations.
def createGame(name, platform, dateAdded, tpe):
return Game(name, platform, dateAdded)
def createFilm(name, platform, dateAdded, tpe):
return Film(name, platform, dateAdded)
Unless there's more stuff happening in these functions which you've
stripped out for clarity you could just call the object constructors
directly from the if statements:
if data['tpe'] == 'Game':
a = Game(name, platform, dateAdded)
game = {a: tpe}
media.append(game)
Why would I only get one object in media, even though all three are
created?
As you may gather, all three input lines are processed, but only one
gets turned into an object to add to media. Change the if/if into an
if/elif/else and see if things become more obvious.
Cheers,
Cameron Simpson
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Re: [Tutor] Only appending one object to list, when I am expecting more than 1
Sorry folks - my code didn't work due to my debug var count to ensure that
I was looping properly.
It should be:
media = []
def loadFile():
filename = input('Filename? ')
f = open(filename, 'r')
createObjects(f)
def createObjects(f):
'''Takes a file object and iterates through entries, passing them to
create
object, depending on what object it is.'''
for line in f:
data = json.loads(line)
print(type(data['tpe']))
name = data['name']
platform = data['platform']
dateAdded = data['dateAdded']
tpe = data['tpe']
if data['tpe'] == 'Game':
a = createGame(name, platform, dateAdded,tpe)
game = {a: tpe}
media.append(game)
if data['tpe'] == 'Film':
a = createFilm(name, platform, dateAdded,tpe)
film = {a: tpe}
media.append(film)
# For some reason I'm only getting one object at a time now when
appending to media
print(len(media))
def createGame(name, platform, dateAdded, tpe):
return Game(name, platform, dateAdded)
def createFilm(name, platform, dateAdded, tpe):
return Film(name, platform, dateAdded)
Also, there is a bug that places an instance variable of dateAdded to tpe,
which is causing an error. This might be why I'm not getting more objects
than I expect.
My class is:
import datetime
class Media:
def __init__(self, name, platform, tpe):
self.name = name
self.platform = platform
date = datetime.datetime.now()
datestring = date.strftime("%Y:%m:%d:%H:%M:%s")
self.dateAdded = datestring
self.tpe = tpe
#self.dateAdded = datetime.datetime.now()
and
from . import media
#import media
class Game(media.Media):
#tpe = 'game'
# def __init__(self):
#self.type = 'game'
Thanks.
Adam
On Tue, 26 Feb 2019 at 10:02, Cameron Simpson wrote:
> Thank you for a well formed problem description.
>
> However, as Steven has remarked the code you've included doesn't run.
> Can you follow up/reply with your actual working script, and also
> include some of the output you get.
>
> That said, I've a few small remarks about the code you have posted:
>
> On 26Feb2019 09:09, AdamC wrote:
> >I'm creating lots of objects from json in a file. Part of reading the json
> >back means that it iterates over the file and loads a json object and then
> >creates the object from the dictionary.
> >
> >This is my file:
> >
> >{"name": "Dwarf Fortress", "platform": "steam", "dateAdded":
> >"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756942"}
> >{"name": "Jaws", "platform": "Netflix", "dateAdded":
> >"2019:02:25:16:56:1551113768", "tpe": "2019:02:21:13:49:1550756960"}
> >{"name": "Wargames", "platform": "CLI", "dateAdded":
> >"2019:02:25:16:59:1551113984", "tpe": "Game"}
>
> BTW, I notice that only one of these rows has the "tpe" field set to
> "Game" or "Film", specificly the last one. So based on your code below,
> only one of these rows gets appended to the media array. Remarks below
> on writing code which is less prone to hiding this kind of problem.
>
> >and these are the functions that help load that file:
> >
> >media = []
> >
> >def loadFile():
> >filename = input('Filename? ')
> >f = open(filename, 'r')
> >createObjects(f)
>
> This f=open code would normally be written like this:
>
> with open(filename, 'r') as f:
> createObjects(f)
>
> That construction ensures that the file gets closed after running
> "createObjects()". As it is in your code the file is not explicitly
> closed; the CPython interpreter will, as it happens, close the file
> pretty promptly when "f" goes out of scope, but the language definition
> doesn't require such immediacy.
>
> >def createObjects(f):
> >'''Takes a file object and iterates through entries, passing them to
> >create
> >object, depending on what object it is.'''
> >for line in f:
> >count = count + 1
> >data = json.loads(line)
> >print(type(data['tpe']))
> >name = data['name']
> >platform = data['platform']
> >dateAdded = data['dateAdded']
> >tpe = data['tpe']
> >if data['tpe'] == 'Game':
> >a = createGame(name, platform, dateAdded,tpe)
> >game = {a: tpe}
> >media.append(game)
> >if data['tpe'] == 'Film':
> >a = createFilm(name, platform, dateAdded,tpe)
> >film = {a: tpe}
> >media.append(film)
>
> These if statements don't cover the case when "tpe" isn't "Game" or
> "Film", and (in other circumstances) could conceivably add two objects.
> If you construct it like this instead:
>
> if data['tpe'] == 'Game':
> a = createGame(name, platform, dateAdded,tpe)
> game = {a: tpe}
> media.append(game)
> elif data['tpe'] == 'Film':
> a = createFilm(name, platform, dateAdded,tpe)
> film = {a: tpe}
>
Re: [Tutor] Only appending one object to list, when I am expecting more than 1
On 2/26/19 6:39 AM, AdamC wrote: Sorry folks - my code didn't work due to my debug var count to ensure that I was looping properly. It should be: As was pointed out, the problem is not in your code. It's in your data. You only have one record with a proper 'tpe' value, so that's all you get in your media list. Toby ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] Doubt
is it possible reverse inheritance? mean child class to parent class ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
[Tutor] I flip a coin 1 million times what is the consecutive times it will come up head and come up tails
I am learning python. I wanted to test my ability by making a program to
keep track of the flip of a coin to find how many consecutive times it came
up heads and tails.
Just want some criticism on what I have done.
import random
Hn = {}
Tn = {}
for i in range (0,31):
vars()["Hn"+str(i)] = 0
for i in range (0,31):
vars()["Tn"+str(i)] = 0
total_Heads = 0
total_tails= 0
tails_number = 0
Heads_number = 0
tries = 0
while tries < 1:
tries += 1
coin = random.randint(1, 2) # Flip coin
if coin == 1:
Heads_number += 1 # Incroment Heads count
total_Heads += 1
if tails_number > 0 :
vars()["Tn"+ str(tails_number)] += 1 # Incroment tails
consecutive count
tails_number = 0
if coin == 2:
tails_number += 1 # Incroment Talies count
total_tails += 1
if Heads_number > 0:
vars()["Hn"+ str(Heads_number)] += 1 # Incroment Heads
consecutive count
Heads_number = 0
print (tries)
print (total_tails, total_Heads)
for i in range (30):
print ('%-15s %-15s' %(("Tn"+str(i)+"
"+str(eval("Tn"+str(i,("Hn"+str(i)+" "+str(eval("Hn"+str(i))
print out
1
5259 4741
Tn0 0 Hn0 0
Tn1 12497339Hn1 12500186
Tn2 6257043 Hn2 6251565
Tn3 3120686 Hn3 3127257
Tn4 1563418 Hn4 1561175
Tn5 781938 Hn5 779381
Tn6 390943 Hn6 389768
Tn7 195569 Hn7 196513
Tn8 97091 Hn8 97858
Tn9 48717 Hn9 48745
Tn10 24493 Hn10 24429
Tn11 11966 Hn11 12237
Tn12 6070 Hn12 6062
Tn13 3021 Hn13 3039
Tn14 1540 Hn14 1556
Tn15 679Hn15 726
Tn16 403Hn16 389
Tn17 179Hn17 206
Tn18 94 Hn18 105
Tn19 49 Hn19 45
Tn20 26 Hn20 24
Tn21 16 Hn21 13
Tn22 5 Hn22 2
Tn23 1 Hn23 3
Tn24 2 Hn24 3
Tn25 1 Hn25 2
Tn26 0 Hn26 0
Tn27 0 Hn27 0
Tn28 0 Hn28 0
Tn29 0 Hn29 0
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Re: [Tutor] Doubt
On 26/02/2019 18:36, Maninath sahoo wrote: > is it possible reverse inheritance? > mean child class to parent class I have no idea what you mean by that. How would it work? Can you give an example of the kind of thing you want to do? For example Circles and Rectangles are kinds of Shape so their classes inherit from class Shape. How would you reverse the inheritance in that scenario? What would you do with it? -- 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] I flip a coin 1 million times what is the consecutive times it will come up head and come up tails
On 26/02/2019 20:34, shaef...@q.com wrote:
> I am learning python.
I assume you are coming from some other language?
If not you have managed to come up with the most
convoluted and un-pythonic way imaginable to do
a fairly simple task!
> I wanted to test my ability by making a program to
> keep track of the flip of a coin to find how many consecutive times it came
> up heads and tails.
>
> import random
>
> Hn = {}
> Tn = {}
>
> for i in range (0,31):
> vars()["Hn"+str(i)] = 0
This is insane!
Just use a list which is indexed by number.
No need for string conversions and no need for
the cumbersome access to vars
Hn = [0 for i in range(31)]
You can then access each cell using
Hn[num]
Instead of having to compute the name every time
and then access a dictionary.
> for i in range (0,31):
> vars()["Tn"+str(i)] = 0
Same here.
> total_Heads = 0
> total_tails= 0
> tails_number = 0
> Heads_number = 0
> tries = 0
> while tries < 1:
> tries += 1
This is essentially a for loop:
for tries in range(1):
> coin = random.randint(1, 2) # Flip coin
> if coin == 1:
> Heads_number += 1 # Incroment Heads count
> total_Heads += 1
> if tails_number > 0 :
> vars()["Tn"+ str(tails_number)] += 1 # Incroment tails
> consecutive count
This becomes
Tn[tails_number] += 1
But why are you incrementing the head counts above but the tails_number
value here? That doesn't make sense. I assume you are trying to
terminate the count of consecutive values?
> tails_number = 0
> if coin == 2:
> tails_number += 1 # Incroment Talies count
> total_tails += 1
> if Heads_number > 0:
> vars()["Hn"+ str(Heads_number)] += 1 # Incroment Heads
> consecutive count
Hn[heads_number] += 1
> Heads_number = 0
> print (tries)
> print (total_tails, total_Heads)
> for i in range (30):
> print ('%-15s %-15s' %(("Tn"+str(i)+"
print('Tn[%d] %d \tHn[%d] %d' % (i,Tn[i],i, Hn[i])
I think. Your code is so complex that I may have misread it.
> "+str(eval("Tn"+str(i,
> ("Hn"+str(i)+" "+str(eval("Hn"+str(i))
Using eval() should hardly ever (never?) be necessary
in normal coding and poses a significant security risk.
Any time you think you need to use it ask for help
because you are probably wrong and there will be a
better option.
> print out
> 1
>
> 5259 4741
>
> Tn0 0 Hn0 0
>
> Tn1 12497339Hn1 12500186
>
> Tn2 6257043 Hn2 6251565
>
> Tn3 3120686 Hn3 3127257
Given you only looped to 10,000 these results seem
rather suspect.
Even if your algorithm is correct, which I suspect
it may not be, the code is way too complex.
If all you want is the max count of consecutive head
and tails you only need to keep one counter for each
and update it each time a new max is reached. Keep
track of the last face. If the new toss is the same
increment the appropriate count. If its not then check
if the current count is greater than the previous max
for that face and if necessary update it. Then reset
the current count and face.
--
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] Doubt
On 2/26/19 11:36 AM, Maninath sahoo wrote: is it possible reverse inheritance? mean child class to parent class Well, it's Python, so you can do all sorts of things, some of them good ideas, some bad... Like Alan says, the question as asked doesn't really make a lot of sense to us, but the way classes (really, user-defined types) work does give you a lot of flexibility. Some people feel like we should express it as code reuse at a sophisticated level: if you see a method in another class that you'd like to use for your own class, you can inherit that method by listing the class in your definition. Or, if you don't want to do so, you write your own method. So while I wouldn't call it reverse inheritance, you as author of your class have all the control of what you do and don't take from other classes, and maybe it's not entirely accurate to call them child and parent classes because of that? ___ Tutor maillist - Tutor@python.org To unsubscribe or change subscription options: https://mail.python.org/mailman/listinfo/tutor
