Create a list from other lists

Question

I have a list {a,b,c,d} and a second list where is how many times the elements of the first list repeat {1,4,2,6} (the order is according with the first list). Then I need to create a third list with this information: {a,b,b,b,b,c,c,d,d,d,d,d,d}. What can I do?

Pretty sure this is a dupe. Anyway: Flatten[MapThread[Table, {{a, b, c, d}, {1, 4, 2, 6}}]] — J. M.'s missing motivation, Mar 22 '18 at 00:53
very closly related / possible duplicate: Convert frequency counts to long notation in Mathematica — kglr, Mar 22 '18 at 01:02

score 1 · Answer 1 · edited Mar 22 '18 at 02:47

1

Catenate @ MapThread[ConstantArray, {{a, b, c, d}, {1, 4, 2, 6}}]

{a, b, b, b, b, c, c, d, d, d, d, d, d}

edited Mar 22 '18 at 02:47

m_goldberg

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answered Mar 22 '18 at 02:25

Alan

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I'm leaving my answer but please vote for this instead (ht kglr). – Alan Mar 22 '18 at 02:29
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Catenate not needed. Flatten@MapThread[ConstantArray, {{a, b, c, d}, {1, 4, 2, 6}}] works. Has advantage of working in older versions without Catenate. – m_goldberg Mar 22 '18 at 03:06

Create a list from other lists

1 Answers1