How to remove spacing in a string?

Question

I am using Python 3.3.

For example, if I opened a file and read the first line using file.readline(), I will get a string of the first line.

Let's say the first line is: line = file.readline().

line will now be: 'Dumbledore, Albus\n'.

If I used:

a = line.strip().split(',')

I will get: ['Dumbledore', ' Albus']

This is where I'm encountering the problem. I do not want the extra space before the first name 'Albus'.

What (simple) approach can I use to remove this?

The purpose of this entire task is to swap the first and last names (for example, from 'Dumbledore, Albus' to 'Albus, Dumbledore'.

Answer 1

Just use str.strip():

s = 'Dumbledore, Albus'
l = [x.strip() for x in s.split(',')]

Answer 2

When you used the strip() function on your readline() output, you used the correct tool that you want to use, albeit at a wrong place.

>>> ' a '.strip()
'a'

Specifically, in your context, you may want to do something like this

>>> a = ['Dumbledore', ' Albus']
>>> a = [x.strip() for x in a]
>>> a
['Dumbledore', 'Albus']

What you are doing is a very simple list comprehension and assigning the final result to the original array.

Answer 3

It is much easier to use a strip or lstrip

a = ['Dumbledore', ' Albus']
a = [item.strip() for item in a]

Given your last edit

names = []
for line in open(myfile).readlines(): #read and act on each line sequentially
    line_list = line.split(',')     # split each line on the comma
    line_list = [item.strip() for line in line_list] # get rid of spaces and newlines
    line_list.reverse()  # reverse the list
    new_name_order = ','.join(line_list)   # join the items with a comma
    names.append(new_name_order)   # add the name to the list of names

Answer 4

The simplest solution is to just split on ', ' instead of ','. So you do:

a = line.strip().split(', ')

Answer 5

You can try in Python:

input = ['Dumbledore', ' Albus']
output = [re.sub(' *', '', x) for x in input]

Answer 6

For completeness you could also use a regular expression:

import re

line = 'Dumbledore, Albus\n'
reformatted = re.sub('(.*?), (.*)', r'\2, \1', line)
# Albus, Dumbledore

Which could be adapted to be:

rx = re.compile('(.*?), (.*?)\n')
with open('yourfile') as fin:
    lines = [rx.sub('\2, \1', line) for line in fin]

Answer 7

As a one-liner:

', '.join([x.strip() for x in line.split(',')][::-1])

Note: [::-1] reverses a list, i.e:

[1, 2, 3][::-1]
=> [3, 2, 1]

A bit clearer for your situation:

lastname, firstname = [x.strip() for x in line.split(',')]
name = firstname + ', ' + lastname