
Re: altering each member of a list that matches a certain pattern
Posted:
Jun 22, 2012 3:00 AM


On Wednesday, June 20, 2012 3:54:33 AM UTC4, Jason Ebaugh wrote: > 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
There is also MapAt:
rs = RandomSample[Range[20], 20]; pos = Position[rs, _?(# > 9&)]; MapAt[SuperStar, rs, pos]

