Re: List Manipulation: Conditionally changing y value when x value

*To*: mathgroup at smc.vnet.net*Subject*: [mg109101] Re: List Manipulation: Conditionally changing y value when x value*From*: Armand Tamzarian <mike.honeychurch at gmail.com>*Date*: Mon, 12 Apr 2010 23:02:07 -0400 (EDT)*References*: <hpml5b$9nk$1@smc.vnet.net>

On Apr 9, 2:31 am, "Charles Koehler" <cjk... at wi.rr.com> wrote: > Hello, > > If possible I could use a little help on this. > > I have a list of x and y data and based on the value of x I would like to > manipulate the value y. > > I joined the data using: > > pts=MapThread[{##1}&,{x,y}] > > I assumed that by testing the x value using #[[1]], I could change the value > of y using #[[2]] as shown below. If no manipulation was required based on > the value of x, I would keep that point unchanged, but I'm definitely > missing something. > > filtered=If[a<#[[1]]&<b,#[[2]]&=0],{#[[1]],#[[2]]}&,pts] > > a and b are the range of x values > > Any insight would be much appreciated. > > Thanks, > > Chuck Koehler Try using a rule replacement. e.g. a=3;b=13; Table[{RandomInteger[{0, 20}], RandomReal[{1, 4}]}, {20}] /. {x_, y_} /; a < x < b :> {x, 0}