Python Test for Full List

Question

I have a list in Python. The list has 5 elements, which can either be "None" or any other string. I want to test if each element is not "None" (that is if all the elements are set).

I've written the following code (where userInventory is the 5-element list) :

 if all(item is not None for item in userInventory):
   print = "Inventory is full, you rat!"
 else:
   ...

For example, ['None', 'Monkey', 'None', 'Jewel', 'None'] should go to the else statement, while ['None', 'None','None','None','None'] should display the message. But right now, the if statement returns true for all the lists...

NOTE The list comes from an HTML form parsed by the cgi library. The data was initially placed by Python and appear like this in HTML : <input type="hidden" name="Inventory1" value="None">

userInventory=[form.getvalue("Inventory1"),form.getvalue("Inventory2"),form.getvalu    e("Inventory3"),form.getvalue("Inventory4"),form.getvalue("Inventory5")]

I am not sure... If I print the list, it appears as 'None' and I am pretty sure that it's the string "None" and not the null value None. — Justin D., Dec 03 '13 at 23:11
Where is the `'None'` string coming from? `None != 'None'`. That would explain why your code is not working. — Jonathon Reinhart, Dec 03 '13 at 23:12
I added a note to explain. I tried with both None and 'None' but neither worked. That's surprising because it works in python interactive. — Justin D., Dec 03 '13 at 23:13
After your edit: Then just change your code to `all(item is not 'None'...` — Jonathon Reinhart, Dec 03 '13 at 23:13

score 5 · Accepted Answer · edited May 23 '17 at 10:32

5

is is used for identity check. Since your list contains string 'None' instead of None, you need to use !=:

item != 'None'

Related: Python is operator?

edited May 23 '17 at 10:32

Community

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answered Dec 03 '13 at 23:15

Ashwini Chaudhary

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This worked, thanks. I am new to Python. I though `is not` was syntactic sugar for `!=`. I'll read about 'identity check'! – Justin D. Dec 03 '13 at 23:17

Python Test for Full List

1 Answers1