Using python to search for string and do something when another string is present

Question

I have a python script that searches through a file:

this is a sample of the input text file:

String A 1
String B 1
String B 2
String B 3
String A 2
String B 4

It stores a numerical value in string A, then does some processing for each existence of a segment of string B where each segment is a different number

y=0
while y < len(InFileStr):
    if "String A" in InFileStr[y]:
        StringA = int(InFileStr[y].split("")[2])
    elif "String B" in InFileStr[y]):
        print "String B" + int(InFileStr[y].split("")[2])"\n"
    y+=1

This "should" produce:

String B 1
String B 2
String B 3
String B 4

where StringA =2 as it's overwritten

However, can't figure out how to just print

String B 1
String B 4

Are you missing a increment at the end of that while loop? Regardless, instead of using a while loop, you should probably use for line in InFileStr. — Daniel Watkins
– Daniel Watkins, Commented Feb 21, 2013 at 13:31
The expected output is that we only process String B twice, not 4 times. — user1862895
– user1862895, Commented Feb 21, 2013 at 13:36
And, presumably, a preceding y = 0. I think we'll need some more clarification of what this is meant to do before we can be much more helpful. — Daniel Watkins
– Daniel Watkins, Commented Feb 21, 2013 at 13:37

pyInTheSky · Accepted Answer · 2013-02-21 14:27:32Z

1

Just trying to interpret what you're looking for, it seems like you just wanted to pair the closest A-string, with a B-string. In which case all you needed was a variable to keep track of the last A string, that way you know you can execute on a B-String. If this is the case, the below code should hopefully work for you.

lastLineStraingA = False

for line in infile.readlines():
    if "StringA" in line:
        lastLineStringA = True
        storeValueInLine(line)
        continue
    elif ("StringB" in line) and (True == lastLineStringA):
        process(line)

    lastLineStringA = False

edited Feb 21, 2013 at 14:27

answered Feb 21, 2013 at 14:16

pyInTheSky

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2 Comments

user1862895 Over a year ago

Excellent man, this works. Apologies to all for the cryptic nature of the question in the first place.

pyInTheSky Over a year ago

no problem. Someone had suggested I edit the post to not have the continue in the if condition. This was done intentionally to capture and correctly set the lastLine variable in the event that you had a String-C. I'm updating the (true) to (True). Since I was in C++ mode :P

Crazyshezy · Accepted Answer · 2013-02-21 14:17:20Z

0

see if this will help you

while y < len(InFileStr):
    if "String A" in InFileStr[y]:
        flag = True    
        storevalueInLine()
    elif "String B" in InFileStr[y]):
        if flag:
            process(StringB)
            flag = False
    y+=1

answered Feb 21, 2013 at 14:17

Crazyshezy

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