Re: altering each member of a list that matches a certain pattern
- To: mathgroup at smc.vnet.net
- Subject: [mg126984] Re: altering each member of a list that matches a certain pattern
- From: Vince Virgilio <blueschi at gmail.com>
- Date: Fri, 22 Jun 2012 02:59:09 -0400 (EDT)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <jrrvjp$4sn$1@smc.vnet.net>
On Wednesday, June 20, 2012 3:54:33 AM UTC-4, 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]