Comment by gandercrews

rewritten apl version w/ lambdas and commute (vs assignment & parens):

          {⍵/⍨⍵<50}{2*⍨⍵/⍨1=2|⍵}⍳10
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About as short as I can make it, and while its longer than the pandas solution, the primitives are significantly more general (sqr, odd - why include these as language primitives?).