Replace the whole string in a list of strings

Question

I have a list of tokens. Some start with an @ sign. I want to change all those strings to a generic @user. I have tried this:

>>> words = ['@john', 'nina', 'michael', '@bebeto']
>>> words = [w.replace(w, '@user') for w in words if w.startswith('@')]
>>> words
['@user', '@user']
>>>

What am I getting wrong here?

What is your desired output?

Ajax1234
– Ajax1234

2017-12-21 18:23:38 +00:00
Commented Dec 21, 2017 at 18:23 — Ajax1234
– Ajax1234, Commented Dec 21, 2017 at 18:23
@Ajax1234 I'd think ['@user', 'nina', 'michael', '@user']

Snow
– Snow

2017-12-21 18:24:27 +00:00
Commented Dec 21, 2017 at 18:24 — Snow
– Snow, Commented Dec 21, 2017 at 18:24

bphi · Accepted Answer · 2017-12-21 18:34:45Z

3

Your list comprehension is causing the undesired output, just change

[w.replace(w, '@user') for w in words if w.startswith('@')]

To

[w.replace(w, '@user') if w.startswith('@') else w for w in words]

edited Dec 21, 2017 at 18:34

answered Dec 21, 2017 at 18:24

bphi

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1 Comment

jbch Over a year ago

That's not valid syntax in Python. See other answers for correct solution.

jbch · Accepted Answer · 2017-12-21 18:31:49Z

2

First of all you can simplify the first part of the list comprehension. This is equivalent and doesn't do a needless replacement:

words = ['@user' for w in words if w.startswith('@')]

In a list comprehension, the if clause at the end decides what is included or not. So the if basically says, only keep elements which starts with '@'. But you want to keep all elements.

Instead you can use a conditional expression to decide whether to get '@user' or the original word:

words = ['@user' if w.startswith('@') else w for w in words]

answered Dec 21, 2017 at 18:31

jbch

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Comments

Ajax1234 · Accepted Answer · 2017-12-21 18:25:56Z

1

You can try this:

words = ['@john', 'nina', 'michael', '@bebeto']
new_words = ['@user' if i.startswith('@') else i for i in words]

Output:

['@user', 'nina', 'michael', '@user']

answered Dec 21, 2017 at 18:25

Ajax1234

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