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altering each member of a list that matches a certain pattern

  • To: mathgroup at smc.vnet.net
  • Subject: [mg126960] altering each member of a list that matches a certain pattern
  • From: Jason Ebaugh <ebaughjason at gmail.com>
  • Date: Wed, 20 Jun 2012 03:51:41 -0400 (EDT)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com

Good people,


I need to alter each member of a list that matches a certain pattern.
However, I need the whole list back, in its original order. 
So Cases[] on its own doesn't do the trick.

Here is a toy example that is analogous to my real problem:
Put an asterisk on each value that is 10 or greater in the following list.

list = RandomSample[Range[20], 20]

Out[1]= {19, 16, 5, 13, 10, 20, 1, 3, 18, 8, 9, 6, 12, 7, 4, 15, 11, 14, 2, 17}

I came up with two ways to do this.
However, I feel like I may be missing a simpler, single function way to do this.

Method 1:
If[# > 9, SuperStar[#], #] & /@ list

Out[2]= {SuperStar[19], SuperStar[16], 5, SuperStar[13], SuperStar[10], 
SuperStar[20], 1, 3, SuperStar[18], 8, 9, 6, SuperStar[12], 7, 4, 
SuperStar[15], SuperStar[11], SuperStar[14], 2, SuperStar[17]}


Method 2:
ReplacePart[list, 
 Table[{Position[list, x_ /; x > 9][[i, 1]] -> 
     Map[SuperStar, Cases[list, x_ /; x > 9]][[i]]}, {i, 
    Length[Cases[list, x_ /; x > 9]]}] // Flatten]

Out[3]= {SuperStar[19], SuperStar[16], 5, SuperStar[13], SuperStar[10], 
SuperStar[20], 1, 3, SuperStar[18], 8, 9, 6, SuperStar[12], 7, 4, 
SuperStar[15], SuperStar[11], SuperStar[14], 2, SuperStar[17]}


Am I missing a more straightforward way to do this?



Thanks,
Jason


Jason Ebaugh



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