string.upto() and string.from()

[ikshefem]

I often need to re-code for myself a small code snippet to define
string.upto() and string.from(), which are used like :

# canonical examples

"1234456789".upto("45") '1234'
"123456dd987".from('d')

'd987'

# if not found, return whole string

"hello, world !".upto("#") "hello, world !"
u"hello, world !".from("#")

u"hello, world !"

"123456dd987".from('d',2) # second integer argument

'987'

# It can be negative, too

'192.168.179.131'.upto(".",-1) "192.168.179"
"192.168.179.131".from('.',-1)

"131"

# useful example

bigstring.upto("\n")

"first line of bigstring"

(I admit I am only using upto, but ...)

Nothing very complicated to make with find and rfind, but wouldn't this
be handy to have it ready in the common string method ?

 

[Duncan Booth]

I often need to re-code for myself a small code snippet to define
string.upto() and string.from(), which are used like :

Nothing very complicated to make with find and rfind, but wouldn't this
be handy to have it ready in the common string method ?

Something similar to this was discussed at length on the development list
last year. I don't think the discussion reached any concrete decision, but
the proposal was to add partition and rpartition methods to strings:

As described by Time Delaney:

partition() splits a string into 3 parts - the bit before the
first occurrance of the separator, the separator, and the bit
after the separator. If the separator isn't in the string at
all then the entire string is returned as "the bit before" and
the returned separator and bit after are empty strings.

See http://thread.gmane.org/gmane.comp.python.devel/70739

 

[Fredrik Lundh]

I often need to re-code for myself a small code snippet to define
string.upto() and string.from(), which are used like :

# canonical examples
'd987'

# if not found, return whole string
u"hello, world !"

'987'

# It can be negative, too
"131"

# useful example
"first line of bigstring"

(I admit I am only using upto, but ...)

Nothing very complicated to make with find and rfind, but wouldn't this
be handy to have it ready in the common string method ?

somewhat related:

http://www.python.org/dev/summary/2005-08-16_2005-08-31.html#str-find

</F>

 

[Kent Johnson]

FWIW this is pretty easy to do with str.split() and rsplit():
"1234456789".split("45", 1)[0]
'1234'
"1234456789".rsplit("45", 1)[-1]
'6789'


"hello, world !".split("#", 1)[0]
'hello, world !'

"hello, world !".rsplit("#", 1)[-1]
'hello, world !'

Kent

 

[ikshefem]

Sure, you're right I forgot about rsplit !
I guess the negative indexes & al could be done with

sep.join(xyz.split(sep)[:index])


Thanks !

 

[Kent Johnson]

Sure, you're right I forgot about rsplit !
I guess the negative indexes & al could be done with

sep.join(xyz.split(sep)[:index])

For index=-1 use
xyz.rsplit(sep, 1)[0]

Kent