Re: Using Cases or Position to Find Strings in a List of Strings
- To: mathgroup at smc.vnet.net
- Subject: [mg119516] Re: Using Cases or Position to Find Strings in a List of Strings
- From: Albert Retey <awnl at gmx-topmail.de>
- Date: Tue, 7 Jun 2011 08:13:48 -0400 (EDT)
- References: <iskvlh$5rm$1@smc.vnet.net>
Hi,
> I have a list of strings called myListOfFilePaths and I want to find
> which one of those strings ends in ".DS_Store" (a hidden file created by
> the Mac OS). I can pick it off using Select as
>
> Select[myListOfFilePaths, StringMatchQ[#, ___ ~~ ".DS_Store" ~~
> EndOfString]&]
>
> but I can't do it using Cases or Position
>
> Cases[myListOfFilePaths, ___ ~~ ".DS_Store" ~~ EndOfString]
>
> Position[myListOfFilePaths, ___ ~~ ".DS_Store" ~~ EndOfString]
>
> despite the fact that Head[___ ~~ ".DS_Store" ~~ EndOfString] is StringExpression. What am I doing wrong?
you need StringCases if your pattern are StringExpressions. For Position
the situation is more complicated, since StringPosition will return a
list of the positions within each string, not just the position of the
string within the list. But you can always do something like this:
Cases[myListOfFilePaths, _String?(StringMatchQ[#, ___ ~~ ".DS_Store" ~~
EndOfString]&), {1}]
Position[myListOfFilePaths, _String?(StringMatchQ[#, ___ ~~ ".DS_Store"
~~ EndOfString] &), {1}]
hth,
albert