That's the input I've put
dagny[x_] := x^2;
Map[dagny, {4, 9, {8, {5}}, {2, 3}}, {2}]
Output:
{4, 9, {64, {25}}, {4, 9}}
But this not I want.
I wanna {4, 9, {64, {5}}, {4, 9}}
How to Map that at a specific Level?
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2 Answers
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ClearAll[dagny]
dagny[x : Except[_List]] := x^2;
dagny[x_] := x
Map[dagny, {4, 9, {8, {5}}, {2, 3}}, {2}]
{4, 9, {64, {5}}, {4, 9}}
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5
Do you mean this?
MapAt[dagny, {4, 9, {8, {5}}, {2, 3}}, {{3, 1}, {4}}]
answered Jan 29, 2020 at 6:12
A little mouse on the pampasA little mouse on the pampas
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$\begingroup$ Nope. Map at a specific level. You're trying to do with the position in a list. What I want here is a a level stuff. $\endgroup$– kileJan 29, 2020 at 6:16
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1$\begingroup$ @kile, then you need to modify the function you're mapping:
Map[If[! ListQ[#], #^2, #] &, {4, 9, {8, {5}}, {2, 3}}, {2}]$\endgroup$ Jan 29, 2020 at 6:19 -
1$\begingroup$ @J.M. For more generality, I recommend
AtomQ. $\endgroup$ Jan 29, 2020 at 6:28 -
$\begingroup$ @bcegkmqs23 how to achieve that with
AtomQ?can u write it in the answer? $\endgroup$– kileJan 29, 2020 at 6:34 -
1$\begingroup$ @kile, Compare and contrast:
Map[If[AtomQ[#], #^2, #] &, {4, 9, {8, {5}}, {2, 3}}, {2}]. Alternatively, you could modify the definition of your function to be mapped:dagny[x_?AtomQ] := x^2; dagny[x_] := x. $\endgroup$ Jan 29, 2020 at 6:41