[Tutor] Searching a text file's contents and comparing them toalist

[christopher.henk at allisontransmission.com]

Eric Hamiter wrote on 07/14/2010 04:57:57 PM:

> Thanks for the pointers! This is now working, albeit probably ugly and 
clunky:
> 
> 
> aisle_one = ["chips", "bread", "pretzels", "magazines"]
> aisle_two = ["juice", "ice cream"]
> aisle_three = ["asparagus"]
> 
> def find_groceries():
>     with open("grocery_list.txt") as grocery_list:
> 
>         first_trip = ["Located on aisle 1: "]
>         second_trip = ["Located on aisle 2: "]
>         third_trip = ["Located on aisle 3: "]
>         no_trip = ["Not found in the database: "]
> 
>         for item in grocery_list:
>             item = item.rstrip()
>             if item in aisle_one:
>                 first_trip.append(item)
>             elif item in aisle_two:
>                 second_trip.append(item)
>             elif item in aisle_three:
>                 third_trip.append(item)
>             else:
>                 no_trip.append(item)
> 
>     sorted_list = first_trip, second_trip, third_trip, no_trip
>     print sorted_list
> 
> find_groceries()
> 
> 
> Last question (for today, at least): Right now, the output is less
> than aesthetically pleasing:
> 
> (['Located on aisle 1: ', 'bread', 'magazines'], ['Located on aisle 2:
> ', 'juice', 'ice cream'], ['Located on aisle 3: ', 'asparagus'], ['Not
> found in the database: ', 'butter', 'soap'])
> 
> How can I format it so it looks more like this:
> 
> Located on aisle 1:
> bread
> magazines
> 
> Located on aisle 2
> [etc...]
> 
> 
> I tried putting "\n" into it but it just prints the literal string.
> I'm sure it has to do with the list format of holding multiple items,
> but so far haven't found a way to break them apart.
> 


your sorted_list is a tuple of lists so when you print it python is 
showing you that structure.
You want the contents of each of those lists printed in a more readable 
format, so you need to loop through the tuple to get each list(trips down 
an aisle)and then within that loop, loop through each list to print each 
item.

in pseudo code to output like you suggest

for each aisle_list in sorted_list
        for each item in the aisle_list
                print the item
        print the space (to separate the aisles, this is part of the loop 
through the tuple, so will run once for each aisle)


Instead of replacing the print statement with the above, I would have this 
as another function which takes sorted_list as a parameter, changing 
find_groceries to return sorted_list instead of printing it.  This keeps 
the two tasks separate and easier to understand and/or debug.

so the last lines of your program are:
sorted_list=find_groceries()
print_shoppinglist(sorted_list)

instead of just calling find_groceries()


Chris
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