How can I rewrite my conditional statement to don't print -1?

Question

My if statement looks weird, but I can't think of how I prevent of -1 value from printing :

### script counts the number of times that a key string appears in target string 

from string import *

def countSubStringMatch(target,key):
    value = target.find(key, 0)
    print value

    while value > -1:
        value = value + 1
        value = target.find(key, value)

        if value != -1:
            print value
        else:
            break

countSubStringMatch("atgacatgcacaagtatgcat","atg")

This is my output:

0
5
15

You're method is almost certainly not the best way of tackling this problem. But I think you should replace the print within the function definition with a return. Could you show the output of the function you call in an edit? — draco_alpine, Jul 19 '16 at 20:13

score 2 · Accepted Answer · answered Jul 19 '16 at 20:11

You can remove the initial print statement, and instead print the value at the beginning of the body of your loop, rather than at the end.

def countSubStringMatch(target,key):
    value = target.find(key, 0)

    while value > -1:
        print value

        value = value + 1
        value = target.find(key, value)

By the way, if you just want the number of matches and not the index of the start of each match, you can use count:

>>> count("atgacatgcacaagtatgcat","atg")
# 3

score 2 · Answer 2 · edited May 23 '17 at 10:28

2

Please use as much as possible the code, other people have already written. Based on Find all occurrences of a substring in Python:

string = "atgacatgcacaagtatgcat"
print [i for i in range(len(string)) if string.startswith('atg', i)]

edited May 23 '17 at 10:28

Community

1
1

answered Jul 19 '16 at 20:25

Ohumeronen

1,769
2
14
28

score 1 · Answer 3 · answered Jul 19 '16 at 20:27

1

def countSubStringMatch(target,key):
   res = set( [ data.find('atg',i) for i in range(len(data)) ] )
   res.remove(-1)
   print res

countSubStringMatch("atgacatgcacaagtatgcat","atg")

set([0, 5, 15])

answered Jul 19 '16 at 20:27

galaxyan

5,944
2
19
43

How can I rewrite my conditional statement to don't print -1?

3 Answers3