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Mathematics Mathematica Wolfram Language

populate a list based on output from multiple lists

bored dude

Posted 10 years ago

Suppose you have the following lists ans = {a1, a2, a3, a4, a5, a6}; bns = {b1, b2, b3, b4, b5, b6, b7, b8}; And the following output. (* Out[69]= {26., {a1 -> 0., a2 -> 0., a3 -> 0., a4 -> 0., a5 -> 0., a6 -> 1., b1 -> 0., b2 -> 0., b3 -> 0., b4 -> 0., b5 -> 1., b6 -> 0., b7 -> 0., b8 -> 1.}} ) How do I automatically create a list so that I have list of a and bs that were given the output of 1. is this case, {a6, b5, b8} And if you have the following lists, as = {3, 1, 4, 5, 5, 8}; an = {100, 50, 100, 150, 50, 100}; ans = {a1, a2, a3, a4, a5, a6}; bs = {3, 5, 1, 6, 8, 5, 5, 10}; bn = {100, 200, 150, 50, 150, 200, 50, 150}; bns = {b1, b2, b3, b4, b5, b6, b7, b8}; how will I populate a list to have the following structure based on that output from above? {a6, 100, 8} (a6 from "ans list", 100 from "an list" corresponding to a6, and 8 from "as list" also corresponding to a6 position.*) {b5, 150, 8, b8, 150, 10} I need to learn to do it so that I can apply it to much longer list.

Suppose you have the following lists

ans = {a1, a2, a3, a4, a5, a6};

bns = {b1, b2, b3, b4, b5, b6, b7, b8};

And the following output.

(* Out[69]= {26., {a1 -> 0., a2 -> 0., a3 -> 0., a4 -> 0., a5 -> 0., 
  a6 -> 1., b1 -> 0., b2 -> 0., b3 -> 0., b4 -> 0., b5 -> 1., 
  b6 -> 0., b7 -> 0., b8 -> 1.}} *)

How do I automatically create a list so that I have list of a and bs that were given the output of 1.

is this case,

{a6, b5, b8}

And if you have the following lists,

as = {3, 1, 4, 5, 5, 8};
an = {100, 50, 100, 150, 50, 100};
ans = {a1, a2, a3, a4, a5, a6};
bs = {3, 5, 1, 6, 8, 5, 5, 10};
bn = {100, 200, 150, 50, 150, 200, 50, 150};
bns = {b1, b2, b3, b4, b5, b6, b7, b8};

how will I populate a list to have the following structure based on that output from above?

{a6, 100, 8} (*a6 from "ans list", 100 from "an list" corresponding to a6, and 8 from "as list" also corresponding to a6 position.*) 

{b5, 150, 8,  b8, 150, 10}

I need to learn to do it so that I can apply it to much longer list.

POSTED BY: bored dude

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bored dude

Posted 10 years ago

Thank you for the reply. And yes, the choice of entry in ans list with 1 will vary each time it's run. it might be 6 now in this example, but it might be a1 that's given 1. So I need a general way to choose the elements if they're given the value of 1 in the following pattern ai-> 1 or bi-> 1...zi->1 Then Look up the corresponding values in the other lists given the chosen ai As in the a6 is in the sixth position of the list and you want all corresponding numbers from the sixth position of the other lists? If yes, then pos = Position[ans, a6]; asVal = Extract[as, pos]; anVal = Extract[an, pos]; Flatten[{a6, anVal, asVal}] This won't work since I have hundreds of list I need to make. This method means I have to type this out hundreds of times. Keys@Select[Association @@ out[[2]], # == 1 &] I don't have the newest mathematica so I don't have the functions you're using.

POSTED BY: bored dude

Kyle Keane

Kyle Keane, Massachusetts Institute of Technology (MIT)

Posted 10 years ago

For some reason, your question is a bit hard for me to follow. For the second part of your question are you always going to have the list in the same order? As in the a6 is in the sixth position of the list and you want all corresponding numbers from the sixth position of the other lists? If yes, then pos = Position[ans, a6]; asVal = Extract[as, pos]; anVal = Extract[an, pos]; Flatten[{a6, anVal, asVal}] I think the first part is answered as follows ans = {a1, a2, a3, a4, a5, a6}; bns = {b1, b2, b3, b4, b5, b6, b7, b8}; out = {26., {a1 -> 0., a2 -> 0., a3 -> 0., a4 -> 0., a5 -> 0., a6 -> 1., b1 -> 0., b2 -> 0., b3 -> 0., b4 -> 0., b5 -> 1., b6 -> 0., b7 -> 0., b8 -> 1.}}; Keys@Select[Association @@ out[[2]], # == 1 &]

For some reason, your question is a bit hard for me to follow. For the second part of your question are you always going to have the list in the same order? As in the a6 is in the sixth position of the list and you want all corresponding numbers from the sixth position of the other lists? If yes, then

pos = Position[ans, a6];
asVal = Extract[as, pos];
anVal = Extract[an, pos];
Flatten[{a6, anVal, asVal}]

I think the first part is answered as follows

ans = {a1, a2, a3, a4, a5, a6}; 

bns = {b1, b2, b3, b4, b5, b6, b7, b8}; 

out = {26., {a1 -> 0., a2 -> 0., a3 -> 0., a4 -> 0., a5 -> 0., 
   a6 -> 1., b1 -> 0., b2 -> 0., b3 -> 0., b4 -> 0., b5 -> 1., 
   b6 -> 0., b7 -> 0., b8 -> 1.}}; 

Keys@Select[Association @@ out[[2]], # == 1 &]

POSTED BY: Kyle Keane

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