Creating a dictionary from a text file
Ok, I'm trying to create a dictionary from a text file, so the key is one lowercase character and each value is a list of words from the file starting with that letter.
The text file contains one line word per line, for example:
airport
bathroom
boss
bottle
elephant
Output:
words = {'a': ['airport'], 'b': ['bathroom', 'boss', 'bottle'], 'e':['elephant']}
Havent gotten very much, just got confused about how I would get the first index from each row and put it as a key and add the values. it would be really helpful if someone can help me figure it out.
words = {}
for line in infile:
line = line.strip() # not sure if this line is correct
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So let's take a look at your example:
words = {}
for line in infile:
line = line.strip()
This looks good to start with. Now you want to do something with line
. You will probably need the first character, which you can access via line[0]
:
first = line[0]
Then you want to check if the letter is already in the dict. If not, you can add a new empty list:
if first not in words:
words[first] = []
Then you can add a word to this list:
words[first].append(line)
And you're done!
If the strings are already sorted like in your example, you can also use itertools.groupby
, which is a little more complicated
from itertools import groupby
from operator import itemgetter
with open('infile.txt', 'r') as f:
words = { k:map(str.strip, g) for k, g in groupby(f, key=itemgetter(0)) }
You can also sort the strings first, which makes this method generally accepted:
groupby(sorted(f), ...)
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defaultdict
from the module collections
is a good choice for tasks like this:
>>> import collections
>>> words = collections.defaultdict(list)
>>> with open('/tmp/spam.txt') as f:
... lines = [l.strip() for l in f if l.strip()]
...
>>> lines
['airport', 'bathroom', 'boss', 'bottle', 'elephant']
>>> for word in lines:
... words[word[0]].append(word)
...
>>> print words
defaultdict(<type 'list'>, {'a': ['airport'], 'b': ['bathroom', 'boss', 'bottle'], 'e': ['elephant']})
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