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How to compare elements of lists with the same length?

Hi,

I struggle a little bit to find the best function to compare two equal length lists. (should be compared the elements each by each, i.e a>d, b>e etc.)

list1={a,b,c} and list2{d,e,f,}

list1 > list2 ?

then I'd like to get a list of boolean like {TRUE,TRUE,FALSE} OR If{condition,"PASS","FAIL"}

Could you suggest the easiest way/function to do that?

Thank you
POSTED BY: Balazs Kisfali
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Hi everyone,

just for completeness if one is interested in speed:

l1 = RandomReal[1, 100000] - 0.5; l2 = RandomReal[1, 100000] - 0.5;
AbsoluteTiming[Positive[(l1 - l2)]]

enter image description here

where

AbsoluteTiming[Thread[l1 > l2]]

enter image description here

Speed might not be an issue though...

Cheers,

Marco

PS: For all the different approaches that Sander lists the respective values are:

enter image description here
POSTED BY: Marco Thiel

You can use the command Thread, try:

l1 = {a, b, c, d}; l2 = {e, f, g, h};
Thread[l1 > l2]
(* Out:   {a>e,b>f,c>g,d>h} *)

Regards -- Henrik
POSTED BY: Henrik Schachner

Try:

Thread[list1>list2]

list1 or list2 can also be a single number...
POSTED BY: Sander Huisman

Thank you, exactly this I was looking for ...I tried "Map", "Scan+Print", "Condition" etc.
POSTED BY: Balazs Kisfali

Thanks a lot

POSTED BY: Balazs Kisfali

Note that you can do it in more than 1 way:

list1={1,2,3}
list2={2.5,2,1.5}
Thread[list1<list2]
Map[#[[1]]<#[[2]]&,{list1,list2}\[Transpose]]
Apply[#1<#2&,{list1,list2}\[Transpose],{1}]
Apply[Less,{list1,list2}\[Transpose],{1}]
Less@@@({list1,list2}\[Transpose])
MapThread[Less,{list1,list2}]
Table[list1[[i]]<list2[[i]],{i,Length[list1]}]

I came up with these ways! and there are probably more!
POSTED BY: Sander Huisman

And if you want to know whether every element of list1 is greater than the corresponding element of list2, then include one more thing:

And @@ Thread[list1 > list2]
POSTED BY: Murray Eisenberg

Though, generally faster would be:

AllTrue[{list1, list2}\[Transpose], Less @@ # &]

Because that one will stop after the first False is found...
POSTED BY: Sander Huisman

Dear Gents, It is so nice to see how this community works ;) Thanks for all the ideas, ...of course I look for the most simplest one, and the below works well for me at the moment.

In[6]:= deal = Thread[list1 > list2]
Out[6]= {False, False, True}

However, I needed something after then the conditions was evaluated, and I was able to program only with one out put, like this

In[7]:= deal = Thread[list1 > list2] /. x_ /; x == True -> "PASS"
Out[7]= {False, False, "PASS"}

Could you please suggest maybe a way where I can pass 2 possible outputs from the boolean? Since I have false OR true output from "Thread[]" (but with condition I could pass only one output) for instance: If x return false, then "FAIL" should be passed into the list

Thanks again
POSTED BY: Balazs Kisfali

How about: 

l1 = RandomInteger[2, 10];
l2 = RandomInteger[1, 10];
Thread[l1 > l2] /. {False -> "FAIL", True -> "PASS"}
(* Out (e.g.):   {"FAIL","FAIL","FAIL","PASS","PASS","PASS","FAIL","PASS","PASS", "PASS"}  *)
POSTED BY: Henrik Schachner

@Henrik, sorry for the late reply but I missed somehow the notification from the Wolfr community.

That was my wish to apply more output based on the boolean. Thanks a lot.

Best regards, Balazs
POSTED BY: Balazs Kisfali

I'm surprised by three things:

method 3 and 4 has a big difference for the same thing.

1 is slower than 6!

and that mapthread is the fastest....
POSTED BY: Sander Huisman
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