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MathGroup Archive 1998

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Re: String patterns


  • To: mathgroup@smc.vnet.net
  • Subject: [mg10930] Re: String patterns
  • From: Paul Abbott <paul@physics.uwa.edu.au>
  • Date: Thu, 12 Feb 1998 20:16:13 -0500
  • Organization: University of Western Australia
  • References: <6brf6t$e78@smc.vnet.net>

MJE wrote:

> How good is Mathematica at this kind of string manipultion and
> searching?

Here is a basic implementation:

In[1]:= string="I love Mathematica"; In[2]:= chars=Characters[string]
In[3]:= ToUpperCase[chars]

Select all upper case letters (and " ",".","-",":"):

In[4]:= Select[%,UpperCaseQ[#]||
      MemberQ[ToCharacterCode/@{" ",".","-",":"},ToCharacterCode[#]]&]

Form the trigraphs explicitly

In[5]:= trigraphs=Apply[StringJoin,Partition[%,3,1],{1}]

and compute the frequencies:

In[6]:=<<Statistics`DataManipulation` In[6]:=
Reverse/@(Frequencies[trigraphs]//Sort//Reverse)//TableForm

Out[6]//TableForm=
MAT   2
VE    1
TIC   1
THE   1
OVE   1
 MA   1
...

There is probably a neat pattern-matching way of computing the
frequencies without constructing the trigraphs explicitly.
 
Cheers,
	Paul 

____________________________________________________________________ 
Paul Abbott                                   Phone: +61-8-9380-2734
Department of Physics                           Fax: +61-8-9380-1014
The University of Western Australia            Nedlands WA  6907       
mailto:paul@physics.uwa.edu.au  AUSTRALIA                            
http://www.pd.uwa.edu.au/~paul

            God IS a weakly left-handed dice player
____________________________________________________________________



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