How to match substring in a string using Python

Question

I have a list of substrings that I have to match in a string iteratively; if matching then perform the desired functionality.

The problem is that, whenever I tried to access the list with loops it does not work. Otherwise if I hard code it then it works. I do not understand why it is so?

My code is here:

players_list = ['Circket', 'PSL', 'IPL', 't20', 'shahid afridi', 'aamer yamin']
length = len(players_list)
cur.execute("SELECT tweet FROM tweets_data")  # Query for getting specific attribute
length = len(players_list)
for row in cur.fetchall():
    i = 0
    while (i<length):
        #print players_list[i], 'tweet value', row
        if players_list[i] in row:
            print 'list item:', players_list[i]
            print row
        else:
            print 'Else statement.'
        i+=1

Output: it should display the rows only that match with the any of the substring value like:

substring is: cricket
row: Security officials concerned about cricket teams being named after militants

"it does not work" is not very informative. Please describe the actual problem in more detail. What is the expected output versus the actual output? — John Coleman, Jun 12 '16 at 12:32
Players_list[i] in row only matches an exact, complete, same item in row. Try printing row, what Is in it? — DisappointedByUnaccountableMod, Jun 12 '16 at 12:32
@IronFist The code looks fine (even if somewhat unpythonic). I think that this is a case of OP expecting one thing but getting another. — John Coleman, Jun 12 '16 at 12:35
@JohnColeman..did u mean like an [X-Y](http://meta.stackexchange.com/questions/66377/what-is-the-xy-problem) problem?...I asked for traceback because he said with iterating through list in loops didn't work, so I was expecting that he got an error message. — Iron Fist, Jun 12 '16 at 12:38
@IronFist Just guessing, I think that OP want's a case-insensitive search but is conducting a case-sensitive search. They seem to describe it as a failure to loop, but the syntax of the loop look fine (unless I am missing something) so I don't think that this is the problem. — John Coleman, Jun 12 '16 at 12:42
@IronFist there is no traceback error/message. Every time it executes the else statement. — SmartF, Jun 12 '16 at 12:50
@PM2Ring assume its all in lower case. still not working. Its strange that if statement does nit executes even if the row has substring . Output is : Else statement. WATCH: Nathan McCullum takes a stunning diving catch against India at the #WT20 Else statement. WATCH: Nathan McCullum takes a stunning diving catch against India at the #WT20 list item: t20 WATCH: Nathan McCullum takes a stunning diving catch against India at the #WT20 — SmartF, Jun 12 '16 at 13:06

score 1 · Answer 1 · answered Jun 12 '16 at 12:51

1

You seem to have a typo with Circket. Also, there is no need to use indices -- just loop over players_list directly, making sure that both the player and the row have a predictable case. Something like:

players_list=['Cricket','PSL','IPL','t20','shahid afridi','aamer yamin']

cur.execute("SELECT tweet FROM tweets_data")  # Query for getting specific attribute
for row in cur.fetchall():
    for player in players_list: 
        if player.lower() in row.lower():
            print 'list item:', player
            print row
        else:
            print 'Else statement.'

answered Jun 12 '16 at 12:51

John Coleman

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It'd be more efficient to convert the strings in `players_list` to lower case before the loops. – PM 2Ring Jun 12 '16 at 12:53
1

You can `break` out of the inner loop after getting a match, as the question says at least one match is enough. Otherwise same `row` will get printed for every word it matches. – Rahul Jun 12 '16 at 12:54
@PM2Ring That is doubtless correct in some ways, though there is a chance that the original cases might be important for some purposes. A lower-cased copy of the list can be created, and perhaps converted to a set so that a set intersection (against `set(row.lower().split())`) could replace the inner loop. My guess is that the problem size is too small for these sorts of things to matter much. – John Coleman Jun 12 '16 at 12:58
Fair point. And at this stage, the OP is probably best served by the simplest code that does the job. – PM 2Ring Jun 12 '16 at 13:02
@Rahul Good point, although the question itself seems somewhat vague about exatly what the intended output should be. – John Coleman Jun 12 '16 at 13:04

score -1 · Accepted Answer · edited Jul 31 '18 at 01:24

-1

If I understood your question correctly, you can try this:

players_list = ['Cricket', 'PSL', 'IPL', 't20', 'shahid afridi', 'aamer yamin']
cur.execute("SELECT tweet FROM tweets_data")
for row in cur.fetchall():
    if any(True for p in players_list if p.lower() in row.lower()):
        print(row)
    else:
        print ("Else statement")

edited Jul 31 '18 at 01:24

Peter Mortensen

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answered Jun 12 '16 at 13:45

Ravi Kumar

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Thank you.you solved my problem. One thing i have to use the player_list value on each iteration like i have to print player name as well with row. e.g, im doing it like: print(p,':',row) but Error is : p is not defined. any suggestion please.? – SmartF Jun 12 '16 at 15:45

How to match substring in a string using Python

2 Answers2