python - TypeError: expected string or buffer

Question

I have this simple code:

import re, sys

f = open('findallEX.txt', 'r')
lines = f.readlines()
match = re.findall('[A-Z]+', lines)
print match

I don't know why I am getting the error:

'expected string or buffer'

Can anyone help?

Answer 1

lines is a list. re.findall() doesn't take lists.

>>> import re
>>> f = open('README.md', 'r')
>>> lines = f.readlines()
>>> match = re.findall('[A-Z]+', lines)
Traceback (most recent call last):
  File "<input>", line 1, in <module>
  File "/usr/lib/python2.7/re.py", line 177, in findall
    return _compile(pattern, flags).findall(string)
TypeError: expected string or buffer
>>> type(lines)
<type 'list'>

From help(file.readlines). I.e. readlines() is for loops/iterating:

readlines(...)
    readlines([size]) -> list of strings, each a line from the file.

To find all uppercase characters in your file:

>>> import re
>>> re.findall('[A-Z]+', open('README.md', 'r').read())
['S', 'E', 'A', 'P', 'S', 'I', 'R', 'C', 'I', 'A', 'P', 'O', 'G', 'P', 'P', 'T', 'V', 'W', 'V', 'D', 'A', 'L', 'U', 'O', 'I', 'L', 'P', 'A', 'D', 'V', 'S', 'M', 'S', 'L', 'I', 'D', 'V', 'S', 'M', 'A', 'P', 'T', 'P', 'Y', 'C', 'M', 'V', 'Y', 'C', 'M', 'R', 'R', 'B', 'P', 'M', 'L', 'F', 'D', 'W', 'V', 'C', 'X', 'S']