| removing substring from string array [message #53240] |
Mon, 02 April 2007 14:21  |
rchughes
Messages: 26
Registered: April 2006
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Junior Member |
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Hi All,
Does anyone know a quick way to remove the same prefix from all
elements in a string array?
Here is an example:
start with string_array = ['dog.spot', 'dog.rover', 'dog.lucky']
and get ['spot', 'rover', 'lucky']
The only way I know I can do this is with a FOR loop and the
STRSPLIT(string_array[i], '.', /EXTRACT) command. I am hoping someone
could help me out with a much more efficient way if there is one.
Thanks in advance,
Ryan.
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| Re: removing substring from string array [message #53322 is a reply to message #53240] |
Tue, 03 April 2007 08:28  |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Ryan. writes:
> But on second thought, I will use the following to be more robust:
>
> string_array =
> ['dog.spot','cat.betsy','doggy.rover','parrot.bill','dog.luc ky']
> p=strpos(string_array,'.')
> print,strmid(string_array,1#p+1)
Hooray! But, be careful. You don't want to over-design
the thing. :-)
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
Sepore ma de ni thui. ("Perhaps thou speakest truth.")
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| Re: removing substring from string array [message #53323 is a reply to message #53240] |
Tue, 03 April 2007 06:50 |
Ryan.
Messages: 77
Registered: March 2006
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Member |
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But on second thought, I will use the following to be more robust:
string_array =
['dog.spot','cat.betsy','doggy.rover','parrot.bill','dog.luc ky']
p=strpos(string_array,'.')
print,strmid(string_array,1#p+1)
Ryan.
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| Re: removing substring from string array [message #53325 is a reply to message #53240] |
Tue, 03 April 2007 06:21 |
Ryan.
Messages: 77
Registered: March 2006
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Member |
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> print,strmid(string_array,4)
My current need is only for the same prefix so the above line works
but if that changes I will come back and look at all the responses =)
Thanks everyone for all your help.
Ryan.
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| Re: removing substring from string array [message #53333 is a reply to message #53240] |
Mon, 02 April 2007 14:40 |
Jean H.
Messages: 472
Registered: July 2006
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Senior Member |
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rchughes@gmail.com wrote:
> Hi All,
>
> Does anyone know a quick way to remove the same prefix from all
> elements in a string array?
>
> Here is an example:
> start with string_array = ['dog.spot', 'dog.rover', 'dog.lucky']
>
> and get ['spot', 'rover', 'lucky']
>
> The only way I know I can do this is with a FOR loop and the
> STRSPLIT(string_array[i], '.', /EXTRACT) command. I am hoping someone
> could help me out with a much more efficient way if there is one.
>
> Thanks in advance,
> Ryan.
>
Hi,
If you know that every element in the array starts with the prefix, you
can do something like
prefixLength = strlen(prefix)
stringWithoutPrefix = strmid(stringArray, prefixLength)
If some entries may NOT start with the prefix, you can extract the
prefix, verify it and if it is the good one, remove it
prefix_array = strmid(stringArray, 0, prefixLength)
entriesWithThePrefix = where(prefix_array eq rebin(prefix,
n_elements(stringArray))
stringWithoutPrefix = strmid(stringArray[entriesWithThePrefix],
prefixLength)
You might want to do something to keep the entries that do not start
with the prefix
Hope that helps,
Jean
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| Re: removing substring from string array [message #53335 is a reply to message #53240] |
Mon, 02 April 2007 14:54 |
yp
Messages: 42
Registered: February 2005
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Member |
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On Apr 2, 10:21 pm, rchug...@gmail.com wrote:
> Hi All,
>
> Does anyone know a quick way to remove the same prefix from all
> elements in a string array?
>
> Here is an example:
> start with string_array = ['dog.spot', 'dog.rover', 'dog.lucky']
>
> and get ['spot', 'rover', 'lucky']
>
> The only way I know I can do this is with a FOR loop and the
> STRSPLIT(string_array[i], '.', /EXTRACT) command. I am hoping someone
> could help me out with a much more efficient way if there is one.
>
> Thanks in advance,
> Ryan.
string_array = ['dog.spot', 'dog.rover', 'dog.lucky']
tmp=stregex(string_array,'dog.',length=L)
n = 100 ;set max number of characters to be extracted
new_array=transpose((strmid(string_array, L, n))[0,*])
Be cautious when you have a huge string_array...
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| Re: removing substring from string array [message #53336 is a reply to message #53240] |
Mon, 02 April 2007 14:38 |
JD Smith
Messages: 850
Registered: December 1999
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Senior Member |
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On Mon, 02 Apr 2007 14:21:42 -0700, rchughes wrote:
> Hi All,
>
> Does anyone know a quick way to remove the same prefix from all
> elements in a string array?
>
> Here is an example:
> start with string_array = ['dog.spot', 'dog.rover', 'dog.lucky']
>
> and get ['spot', 'rover', 'lucky']
>
> The only way I know I can do this is with a FOR loop and the
> STRSPLIT(string_array[i], '.', /EXTRACT) command. I am hoping someone
> could help me out with a much more efficient way if there is one.
For a fixed length string like this, it's easy:
print,strmid(string_array,4)
But, suppose it's a non-uniform length string:
string_array = ['dog.spot','cat.betsy','doggy.rover','parrot.bill','dog.luc ky']
p=strpos(string_array,'.')
print,strmid(string_array,1#p+1)
Notice that silly use of 1#p. This is to ensure that only 1
sub-string is extracted from each string in the array (try it without
the 1# and you'll see what I mean; see STRMID docs).
Or you could even be more general and use a regular expression:
string_array = ['dog.spot','cat*betsy','doggy#rover','parrot&bill','dog @lucky']
p=stregex(string_array,'^.+[.*#&@]',LENGTH=len)
print,strmid(string_array,1#len)
JD
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