Remove "\n" with strip in Python?

I'm working on a file text, but, as it has spaces at the beginning too, when I try to delete my \n using the strip mode and list comprehension, I get a list with empty elements (" ") and I don't know how to delete them. I have a text and my code is:

with open(filename) as f:
    testo= f.readlines()
[e.strip() for e in testo]

but I get a list like this:

[' ', ' ', 'word1', 'word2', 'word3', ' ']

I wanted to know if I can work it out with the strip method, otherwise with another method.

Solution

You can use a generator to read all the lines and strip() the unwanted newlines.

From the generator you only use those elements that are "Truthy" - empty strings are considered False.

Advantage: you create only one list and get rid of empty strings:

Write file:

filename = "t.txt"
with open(filename,"w") as f:
    f.write("""

  c
  oo
  l

  te
  xt
  """)

Process file:

with open(filename) as f:
    testo = [x for x in (line.strip() for line in f) if x] # f.readlines() not needed. f is
                                                          # an iterable in its own right

print(testo)  # ['c', 'oo', 'l', 'te', 'xt']

You could do the similarly:

testo = [line.strip() for line in f if line.strip()]

but that would execute strip() twice and would be slightly less efficient.

Output:

['c', 'oo', 'l', 'te', 'xt']

Doku:

A suggested alternative from Eli Korvigo is:

testo = list(filter(bool, map(str.strip, f)))

with is essentially the same - replacing the explicit list comp using a generator comp with a map of str.strip on f (resulting in a generator) and applying a filter to that to feed it into a list.

See built in function for the docu of filter,map,bool.

I like mine better though ;o)