[Tutor] Looking for Words - Help

[Peter Otten]

Jackie Canales wrote:

> Need assistance with a questions in regards to python:
> 1. function occurs(name, word) which looks for a word in the file with
> name name. 2. for each occurrence of the word we want to display its
> context by showing the 5 words (or so) preceding and following the
> occurrence, e.g. '... a man to set the river on fire. He had ...' for the
> first occurrence of 'river' in 'innocents.txt'. 3. since the results may
> be long, we want to collect them all, and write them to a file whose name
> should be 'occurs'+name.
> 
> Hint: at first ignore writing the results to a file. Simply collect all
> material in a string which you print to the screen. Then writing it to a
> file will be simple. To get both the word and its context you need an
> indexed loop through the words. Use the stripw() function we saw on
> individual words to make finding hits more accurate (e.g. the program
> found 'river.' above). Finally, the join() method will come in handy to
> reconstruct the context as a string.
> 
> 
> Link to final product: http://imgur.com/q1aAAhp
> 
> For my program this is what i have so far, I am kinda lost at this point
> if you can please guide me to help resolve this program.

> def lines(name, word):
>     'print all lines of name in which word occurs'
> 
>     infile = open(name, 'r')
>     lst = infile.readlines()

You need the words, not the lines, so it is simpler if you read the complete 
file as a string. Next, look for a method to split the string into words and 
apply that.

Once you have the list of words you can iterate over that and the index 
using

for index, word_from_text in enumerate(words):
        ...

Check if word_from_text matches word, and if it does use slicing to get a 
list of words that surround it:

context = words[index-5:index+5]

Come back if you run into problems you can't solve yourself.

>     infile.close()
> 
>     for i in range(len(lst)):
>         line = lst[i]
>         if wordin(word, line):
>             w = ('Word found in line {}:'.format(i))
>             #x = (lst[i+1])
>             y = lst[i]        
>              
>             print (''.join(y))
>