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Re: Mapping A Condition Across Two Different Lists

  • To: mathgroup at smc.vnet.net
  • Subject: [mg91766] Re: Mapping A Condition Across Two Different Lists
  • From: Bill Rowe <readnews at sbcglobal.net>
  • Date: Sun, 7 Sep 2008 05:38:47 -0400 (EDT)

On 9/6/08 at 2:06 AM, gregory.lypny at videotron.ca (Gregory Lypny)
wrote:

>Not sure how to do this using Map, or even if it's possible.

>I can compare a target value to each value in a list like this.

>targetX = 5; listX = {4, 9, 2, 11, 4}; targetX > # & /@ listX

>{True, False, True, False, True}

>I can do the same for another target and another list.
>
>targetY = 3; listY = {4, 0, 1, 8, 6}; targetY > # & /@ listY

>{False, True, True, False, False}

>But can I do it in a similar way for the AND or OR condition without
>having to resort to the Table command?

You could do it with Map as follows:

In[4]:= (targetY > First@# && targetX > Last@#) & /@
 Transpose@{listY, listX}

Out[4]= {False,False,True,False,False}

but MapThread is specifically designed for this task. For example,

In[5]:= MapThread[targetY > #1 && targetX > #2 &, {listY, listX}]

Out[5]= {False,False,True,False,False}



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