reading words from a file into a set, maintaining order

Question

here is an array of Unicode words used in the python script.

texts =[u"abc", u"pqr", u"mnp"]

The script is working as expected with the above 3 words example. The issue is that there are thousands of words in a text file. How do I read from the text file?

Update: I have 2 issues. The sequence of words from the text file is not maintained in the output. The text file has unicode characters and hence the "u" in my original example.

# cat testfile.txt
Testing this file with Python

# cat test.py
#!/usr/bin/python
# -*- coding: utf-8 -*-

f     = open('testfile.txt', 'r')
texts  = set(f.read().split())
print (texts)

# python test.py
set(['this', 'Python', 'Testing', 'with', 'file'])

Answer 1

This is because how sets work. They don't maintain the order of the items stored in the set.

From the documentation:

A set object is an unordered collection of distinct hashable objects

Answer 2

I see no problem with your file reading code. Given that the words appear in the file separated by whitespace, and the file is not too big to be gulped with a single read, it should work just fine. The real problem is the order of the words if you shove them into a set.

If you need the words in the same order as they appear in the file, why are you using a set? Just keep them in a list.

If you need a set to remove duplicates and/or other purposes, then you have the following options:

• Use the OrderedDict class - standard in Python since 2.7, and recipes exist online for earlier versions.
• Create an ordered set - here's a SO question with a good discussion of this