Beginner Q: for loop syntax clarification

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February 8th, 2013, 07:03 AM

pyRookie

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Beginner Q: for loop syntax clarification

I am a complete newbie to Python and need to work with Twitter data using Python on an immediate basis. Can anyone help me understand the last line of the following code? or any pointers to look online. I see there's a for loop but not sure how the iteration works as its different from for specification I came across in Py sofar.

Code:

import twitter # Tell Python to use the twitter package 

twitter_api = twitter.Twitter(domain="api.twitter.com",api_version='1') # create a variable named twitter_api of class "twitter.Twitter()" 

WORLD_WOE_ID = 1 # The Yahoo! Where On Earth ID for the 
entire world 

world_trends = twitter_api.trends._(WORLD_WOE_ID) # get back a callable 

[trend for trend in world_trends()[0]['trends']]

Thanks

February 8th, 2013, 08:28 AM

MrFujin

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Take a look at this page:
https://dev.twitter.com/docs/api/1/get/trends/%3Awoeid

This is what the code connects to and retrieve data from.

February 8th, 2013, 09:07 AM

pyRookie

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Thanks for reply!
I understand the API, but I wanted to know what kind of loop is it in the last line of code I posted in my first post with statement within square brackets []. what is it called?

Quote:

Originally Posted by MrFujin

Take a look at this page:
xx
This is what the code connects to and retrieve data from.

February 8th, 2013, 11:31 AM

b49P23TIvg

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example

Code:

def world_trends():
    LIST = []
    LIST.append( dict( kingsPi = ['22', '/', '7'], trends = (2, 7, 1, 8, 2, )))
    return LIST

print('output of world_trends()')
print(world_trends())

print('')

print('nasty last line of post')
print([trend for trend in world_trends()[0]['trends']])

print('')

print('simplification of nasty last line of post')
print(list(world_trends()[0]['trends']))

1) In your code
[trend for trend in world_trends()[0]['trends']]
is not stored. It would take a contrived example to make this statement have any sort of noticeable side effect.

2) Why not just use world_trends()[0]['trends'] instead? Not all iterables are lists, indeed
dict(a=3) is iterable but
dict(a=3)[0] looks up the value at key 0 not item 0.
list(dict(a=3))[0] == 'a'

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February 8th, 2013, 11:46 AM

pyRookie

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Very clear explanation.. I also understand now why this code did not show any result in my pyCharm IDE output window, while it worked fine on python interpreter console.

thank you very much! :-)

Quote:

Originally Posted by b49P23TIvg

example

Code:

def world_trends():
    LIST = []
    LIST.append( dict( kingsPi = ['22', '/', '7'], trends = (2, 7, 1, 8, 2, )))
    return LIST

print('output of world_trends()')
print(world_trends())

print('')

print('nasty last line of post')
print([trend for trend in world_trends()[0]['trends']])

print('')

print('simplification of nasty last line of post')
print(list(world_trends()[0]['trends']))

February 8th, 2013, 12:32 PM

Dietrich

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Trying to run your code, all I get is ...
AttributeError: 'module' object has no attribute 'Twitter'

I think you get a "JavaScript Object Notation" object. Looks like a Python dictionary.

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Last edited by Dietrich : February 8th, 2013 at 01:04 PM.

Beginner Q: for loop syntax clarification

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