For statement with slice copy

[Truman]

Hi,

I'm looking at this piece of code:

words = ['cat', 'window', 'defenestrate']
for w in words[:]:     
    if len(w) > 6:         
        words.insert(0, w)  
words ['defenestrate', 'cat', 'window', 'defenestrate']

If I understand well it should make copy of the list and add 'defenestrate' into list but I receive a message "tuple object has no attribute instert". This code is a part of a tutorial I'm following and not sure why it doesn't work.

[justsomeguy]

Are you sure that's the exact code you're using?  The error message says you've defined a tuple instead of a list.

[Truman]

It looks so, you can find it here:

https://docs.python.org/3.6/tutorial/controlflow.html

4.2. for Statements

[justsomeguy]

I wasn't referring to the for loop, I was talking about the variable definition.  The error message says you are using a tuple, and like it points out tuples do not have an insert method (you misspelled that in the error message).  If that's true, then it sounds like you've defined the variable using parentheses instead of square brackets, which is why I was asking if that is the actual code you are executing or if you copied and pasted that code from another source.

[Truman]

You're correct but after changing it to square brackets I receive TypeError: list indices must be integer or slices, not tuple.

[justsomeguy]

Post the current code you're using, it's tough when you're using something other than what you posted.  I can only debug what I can see.  If that error is on the insert line then it sounds like you're giving it a tuple instead of an integer for the position to insert.

[Truman]

words = ['book', 'superficial', 'nostradamus']
for w in words:
    print(w, len(w))
for w in words[:]:
     if len(w) > 6:
         words.insert(0, w)
words ['defenestrate', 'cat', 'window', 'defenestrate']

this is my code.

[dsonesuk]

You will find the last part is not part of code, but what will be the result when the code is run and finishes.

replace last line with:

print words

 

 

[dsonesuk]

OR

words = ['book', 'superficial', 'nostradamus']
for w in words:
    print(w, len(w))
for w in words[:]:
     if len(w) > 6:
         words.insert(0, w)

print ('words'+ str(words))

It will print a string representation of words array and its values.

Edited December 6, 2017 by dsonesuk