Reading data from specially formatted text file

Question

I am using this method, kindly suggested by Ashwini Chaudhary, to assign data to a dictionary from a text file that is in a specific format.

keys = map(str.strip, next(f).split('Key\t')[1].split('\t'))
words = map(str.strip, next(f).split('Word\t')[1].split('\t'))

The text file has the row title followed by values, separated by a \t character.

Example 1:

Key      a 1  b 2  c 3  d 4
Word     as   box  cow  dig

How would I change my code not to read all the lines in a file, but only specific ones? Extra Lines which I do not want to read should just be ignored:

Example 2 - ignore LineHere and OrHere rows:

LineHere  w    x    y    z
Key       a 1  b 2  c 3  d 4
OrHere    00   01   10   11
Word      as   box  cow  dig

Or if I wanted to have the possibility of reading a line titled 'Word' XOR 'Letter', whichever one happens to be in the file. So the code to scan Examples 1 or 2 would also be valid for:

Example 3 - I want to read Key and Letter lines:

LineHere  w    x    y    z
Key       a 1  b 2  c 3  d 4
OrHere    00   01   10   11
Letter    A    B    C    D

Please feel free to comment with question criticisms and I'll be happy to rephrase/clarify the question.

As a reference, the precursor question is linked here

Many thanks,

Alex

Answer 1

Something like this:

import re
with open('abc') as f:
    for line in f:
        if line.startswith('Key'):
            keys = re.search(r'Key\s+(.*)',line).group(1).split("\t")
        elif line.startswith(('Word','Letter')):
            vals = re.search(r'(Word|Letter)\s+(.*)',line).group(2).split("\t")

    print dict(zip(keys,vals))

abc:

LineHere  w    x    y    z
Key       a 1  b 2  c 3  d 4
OrHere    00   01   10   11
Word      as   box  cow  dig

output is :

{'d 4': 'dig', 'b 2': 'box', 'a 1': 'as', 'c 3': 'cow'}

abc:

LineHere  w    x    y    z
Key       a 1  b 2  c 3  d 4
OrHere    00   01   10   11
Letter    A    B    C    D

output is :

{'d 4': 'D', 'b 2': 'B', 'a 1': 'A', 'c 3': 'C'}

Answer 2

ss = '''LineHere  w    x    y    z
Key       a 1  b 2  c 3  d 4
OrHere    00   01   10   11
Word      as   box  cow  dig
'''
import re

rgx = re.compile('Key +(.*)\r?\n'
                 '(?:.*\r?\n)?'
                 '(?:Word|Letter) +(.*)\r?\n')

mat = rgx.search(ss)
keys = mat.group(1).split(' ')
words = mat.group(2).split('\t')

You'll obtain ss by reading your file:

with open (filename) as f:
    ss = f.read()

Edit

Well, if all the lines have data separated with tabs, you can do:

ss = '''LineHere  w\tx\ty\tz
Key       a 1\tb 2\tc 3\td 4
OrHere    00\t01\t10\t11
Word      as\tbox\tcow\tdig
'''
import re

rgx = re.compile('Key +(.*)\r?\n'
                 '(?:.*\r?\n)?'
                 '(?:Word|Letter) +(.*)\r?\n')

print  dict(zip(*map(lambda x: x.split('\t'),
                     rgx.search(ss).groups())))