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MathGroup Archive 2012

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Question about DeleteCases to remove list elements based on first character

  • To: mathgroup at smc.vnet.net
  • Subject: [mg124291] Question about DeleteCases to remove list elements based on first character
  • From: Andrew DeYoung <adeyoung at andrew.cmu.edu>
  • Date: Mon, 16 Jan 2012 17:06:38 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Hi,

I have a list of strings in which some elements begin with the ";"
character and some do not.  The ";" character indicates a program
comment, so I wish to drop all elements in the list that begin with
the ";" character.

As a simplified example, suppose I have the following list S:

S = {"abc", ";def", "ghi", ";jkl", ";  mno", "pqr;X"}

I wish to drop from S all elements that begin with ";".  So, I want to
obtain:

{"abc", "ghi", "pqr;X"}

Will you please help me know how to do this?  Can this be done with
DeleteCases?  For example, I tried:

DeleteCases[S, StringTake[#, 1] == ";"&]

and

DeleteCases[S, ";" ~~ __]

but I am wrong:  these do not work.  Can you please help me?

Thanks so much.

Andrew DeYoung
Carnegie Mellon University



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