CODEWITHSUNDEEP
python
Scott
Scott

Reputation: 25

Brain going to explode. Need to search external file and return muliple results

I'm not going to lie. I'm trying to do an assignment and I'm being beaten by it.

I need to have python prompt the user to enter a room number, then lookup that room number in a supplied .txt file which has csv [comma-separated values], and then show multiple results if there are any.

I was able to get python to return the first result ok, but then it stops. I got around the csv thing by using a hash command and .split (I would rather read it as a csv although I couldn't get it to work.) I had to edit the external file so instad of the data being seperated by commas it was seperated by semicolons, which is not ideal as I am not supposed to be messing with the supplied file.

Anyhow... My external file looks like this:

roombookings.txt

6-3-07;L1;MSW001;1
6-3-07;L2;MSP201;1
6-3-07;L3;WEB201;1
6-3-07;L4;WEB101;1
6-3-07;L5;WEB101;1
7-3-07;L1;MSW001;2
7-3-07;L2;MSP201;2
7-3-07;L3;WEB201;2
7-3-07;L4;WEB101;2
7-3-07;L5;WEB101;2
8-3-07;L1;WEB101;1
8-3-07;L2;MSP201;3

Here's what my code looks like:

roomNumber = (input("Enter the room number: "))


def find_details(id2find):
    rb_text = open('roombookings.txt', 'r')
    each_line = rb_text.readline()
    while each_line != '':
        s = {}
        (s['Date'], s['Room'], s['Course'], s['Stage']) = each_line.split(";")
        if id2find == (s['Room']):
                rb_text.close()
                return(s)
        each_line = rb_text.readline()
    rb_text.close()

room = find_details(roomNumber)
if room:
    print("Date: " + room['Date'])
    print("Room: " + room['Room'])
    print("Course: " + room['Course'])
    print("Stage: " + room['Stage'])

If i run the program, I get prompted for a room number. If I enter, say, "L1" I get:

Date: 6-3-07
Room: L1
Course: MSW001
Stage: 1

I should get 3 positive matches. I guess my loop is broken? Please help me save my sanity!

Edit. I've tried the solutions here but keeps either crashing the program (I guess I'm not closing the file properly?) or giving me errors. I've seriously been trying to sort this for 2 days and keep in mind I'm at a VERY basic level. I've read multiple textbooks and done many Google searches but it's all still beyond me, I'm afraid. I appreciate the assistance though.

Upvotes: 1

Views: 178

Answers (3)

Roman Bodnarchuk
Roman Bodnarchuk

Reputation: 29727

First. For iterating over lines in the file use next:

for line in rb_text:
    # do something

Second. Your function returns after first match. How can it match more then one record? Maybe you need something like:

def find_details(id2find):
    rb_text = open('roombookings.txt', 'r')
    for line in rb_text:
        s = {}
        (s['Date'], s['Room'], s['Course'], s['Stage']) = line.split(";")
        if id2find == (s['Room']):
            yield s
    rb_text.close()

And then:

for room in find_details(roomNumber):
    print("Date: " + room['Date'])
    print("Room: " + room['Room'])
    print("Course: " + room['Course'])
    print("Stage: " + room['Stage'])

And yes, you better use some CSV parser.

Upvotes: 1

Sasha
Sasha

Reputation: 326

Your code does "return(s)" the first time the "id2find" argument is exactly equal to the room.

If you want multiple matches, you could create an empty list before entering the loop, append every match to the list WITHOUT returning, return the list, and then use a for-loop to print out each match.

Upvotes: 2

tux21b
tux21b

Reputation: 94699

Your problem is the return(s) in find_details(). As soon as you have found an entry, you are leaving the function. You do not even close the file then. One solution is to use an empty list at the beginning, e.g results = [], and then append all entries which matches your requirements (results.append(s)).

Upvotes: 0

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