Remove trailing newline from the elements of a string list

I have to take a large list of words in the form:

['this\n', 'is\n', 'a\n', 'list\n', 'of\n', 'words\n']

and then using the strip function, turn it into:

['this', 'is', 'a', 'list', 'of', 'words']

I thought that what I had written would work, but I keep getting an error saying:

"'list' object has no attribute 'strip'"

Here is the code that I tried:

strip_list = []
for lengths in range(1,20):
    strip_list.append(0) #longest word in the text file is 20 characters long
for a in lines:
    strip_list.append(lines[a].strip())

You can either use a list comprehension

my_list = ['this\n', 'is\n', 'a\n', 'list\n', 'of\n', 'words\n']
stripped = [s.strip() for s in my_list]

or alternatively use map():

stripped = list(map(str.strip, my_list))

In Python 2, map() directly returned a list, so you didn't need the call to list. In Python 3, the list comprehension is more concise and generally considered more idiomatic.

list comprehension? [x.strip() for x in lst]

You can use lists comprehensions:

strip_list = [item.strip() for item in lines]

Or the map function:

# with a lambda
strip_list = map(lambda it: it.strip(), lines)

# without a lambda
strip_list = map(str.strip, lines)

This can be done using list comprehensions as defined in PEP 202

[w.strip() for w in  ['this\n', 'is\n', 'a\n', 'list\n', 'of\n', 'words\n']]

All other answers, and mainly about list comprehension, are great. But just to explain your error:

strip_list = []
for lengths in range(1,20):
    strip_list.append(0) #longest word in the text file is 20 characters long
for a in lines:
    strip_list.append(lines[a].strip())

a is a member of your list, not an index. What you could write is this:

[...]
for a in lines:
    strip_list.append(a.strip())

Another important comment: you can create an empty list this way:

strip_list = [0] * 20

But this is not so useful, as .append appends stuff to your list. In your case, it's not useful to create a list with defaut values, as you'll build it item per item when appending stripped strings.

So your code should be like:

strip_list = []
for a in lines:
    strip_list.append(a.strip())

But, for sure, the best one is this one, as this is exactly the same thing:

stripped = [line.strip() for line in lines]

In case you have something more complicated than just a .strip, put this in a function, and do the same. That's the most readable way to work with lists.

Remove trailing newline from the elements of a string list

Related

Recent Posts