Strings in Python

[Johny]

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose

mystring='12341 '
import string

>>string.find(m ystring ,'1')

0

But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?
Thanks for help
L

[Gary Herron]

Re: Strings in Python

Johny wrote:

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose
>
mystring='12341 '
import string
>
>

>>>string.find( mystring ,'1')
>>>>

0
>
But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?
Thanks for help
L
>
>

You could use a regular expression. The re module has s function
"findall" that does what you want.

Also, if you read the documentation for strings find method, you'll find:

1 S.find(sub [,start [,end]]) -int
2
3 Return the lowest index in S where substring sub is found,
4 such that sub is contained within s[start,end]. Optional
5 arguments start and end are interpreted as in slice notation.
6
7 Return -1 on failure.

So put your find in a loop, starting the search one past the previously
found occurrence.

i = string.find(mys tring, i+1)

Gary Herron

[Shawn Milo]

Re: Strings in Python

On 8 Feb 2007 08:28:25 -0800, Johny <python@hope.cz wrote:

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose
>
mystring='12341 '
import string
>

>string.find(my string ,'1')

0
>
But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?
Thanks for help
L
>
--

http://mail.python.org/mailman/listinfo/python-list

>

Loop it -- once you know the index of the first character, add the
third argument to string.find(), which tells it the position at which
to start (the last find + 1).

[Shawn Milo]

Re: Strings in Python

On 2/8/07, Gary Herron <gherron@island training.comwro te:

Johny wrote:

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose

mystring='12341 '
import string

>>string.find(m ystring ,'1')
>>>

0

But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?
Thanks for help
L

You could use a regular expression. The re module has s function
"findall" that does what you want.
>
Also, if you read the documentation for strings find method, you'll find:
>
1 S.find(sub [,start [,end]]) -int
2
3 Return the lowest index in S where substring sub is found,
4 such that sub is contained within s[start,end]. Optional
5 arguments start and end are interpreted as in slice notation.
6
7 Return -1 on failure.
>
So put your find in a loop, starting the search one past the previously
found occurrence.
>
i = string.find(mys tring, i+1)
>
Gary Herron
>
>
--

http://mail.python.org/mailman/listinfo/python-list

>

Speaking of regex examples, that's basically what I did in the script
below which James Kim and I were collaborating on yesterday and this
morning, as a result of his thread.

This matches not only a string, but a regex, then loops through each
match to do something to it. I hope this helps. I submitted this to
the list for recommendations on how to make it more Pythonic, but at
least it works.

Here are the most important, stripped down pieces:

#! /usr/bin/python

import re

#match a date in this format: 05/MAR/2006
regex = re.compile(r",\ d{2}/[A-Z]{3}/\d{4},")

for line in infile:

matches = regex.findall(l ine)
for someDate in matches:

newDate = #do something here
line = line.replace(so meDate, newDate)


Here is the full script:

#! /usr/bin/python

import sys
import re

month ={'JAN':1,'FEB' :2,'MAR':3,'APR ':4,'MAY':5,'JU N':6,'JUL':7,'A UG':8,'SEP':9,' OCT':10,'NOV':1 1,'DEC':12}
infile=file('TV A-0316','r')
outfile=file('t mp.out','w')

def formatDatePart( x):
"take a number and transform it into a two-character string,
zero padded"
x = str(x)
while len(x) < 2:
x = "0" + x
return x

regex = re.compile(r",\ d{2}/[A-Z]{3}/\d{4},")

for line in infile:
matches = regex.findall(l ine)
for someDate in matches:

dayNum = formatDatePart( someDate[1:3])
monthNum = formatDatePart( month[someDate[4:7]])
yearNum = formatDatePart( someDate[8:12])

newDate = ",%s-%s-%s," % (yearNum,monthN um,dayNum)
line = line.replace(so meDate, newDate)

outfile.writeli nes(line)

infile.close
outfile.close

[attn.steven.kuo@gmail.com]

Re: Strings in Python

On Feb 8, 8:28 am, "Johny" <pyt...@hope.cz wrote:

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose
>
mystring='12341 '
import string
>

>string.find(my string ,'1')

>
0
>
But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?

In this case, you can use:

mystring = '12341'
indices = [ _ for _ in range(len(mystr ing)) if mystring[_] == '1' ]
print indices

--
Hope this helps,
Steven

[MRAB]

Re: Strings in Python

On Feb 8, 6:32 pm, attn.steven.... @gmail.com wrote:

On Feb 8, 8:28 am, "Johny" <pyt...@hope.cz wrote:
>
>
>

Playing a little more with strings, I found out that string.find
function provides the position of
the first occurance of the substring in the string.
Is there a way how to find out all substring's position ?
To explain more,
let's suppose

>

mystring='12341 '
import string

>

>>string.find(m ystring ,'1')

>

0

>

But I need to find the possition the other '1' in mystring too.
Is it possible?
Or must I use regex?

>
In this case, you can use:
>
mystring = '12341'
indices = [ _ for _ in range(len(mystr ing)) if mystring[_] == '1' ]
print indices
>

Or:

mystring = '12341'
indices = [ i for i, c in enumerate(mystr ing) if c == '1' ]
print indices

[Johny]

Re: Strings in Python

Thanks ALL for help and ideas
L