Converting list of string into integers and reshaping the original list

Question

I have the following list which I am importing from Python - thus the format:

l = {{"a", "[1,2,3,4,5]"}, {"b", "[6,7,8,9,10]"}}

I wonder how can I convert this to the following shape:

{{{"a"}, {1,2,3,4,5}}, {{"b"}, {6,7,8,9,10}}}

Essentially for each letter the numbers in front should be converted to integer and list so one can do operations on them.

Thanks for accepting Coolwater's answer, it's a very good answer, but anyhow I think you were too hasty doing that. While accepting is one of the things to do after your question is answered, we recommend that users should test answers before voting and wait 24 hours before accepting the best one. Even more in this case where there were unresolved questions in the comments. — rhermans, Jul 17, 2019 at 13:07

Coolwater · Accepted Answer · 2019-07-17 11:03:39Z

4

One way:

Replace[l, s_String :> If[StringMatchQ[s, "[" ~~ ___ ~~ "]"],
   ToExpression["{" <> StringTake[s, {2, -2}] <> "}"], {s}], {2}]

answered Jul 17, 2019 at 11:03

Coolwater

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kglr · Accepted Answer · 2019-07-17 12:00:07Z

l /. 
  s_String :> StringReplace[s, "[" ~~ st___ ~~ "]" :> ToExpression["{" <> st <> "}"]] /. 
  StringExpression -> Identity /. 
  s_String :> {s}

{{{"a"}, {1, 2, 3, 4, 5}}, {{"b"}, {6, 7, 8, 9, 10}}}

Also

l1 = l;
l1[[All, 1]] = Map[List]@l[[All, 1]];
l1[[All, 2]] = Map[ToExpression@StringJoin["List", #] &]@l[[All, 2]];
l1

{{{"a"}, {1, 2, 3, 4, 5}}, {{"b"}, {6, 7, 8, 9, 10}}}

l2 = StringReplace[#, {"[" -> "{", "]" -> "}"}] & /@ l;
l2[[All, 1]] = List /@ l2[[All, 1]];
l2[[All, 2]] = ToExpression[l2[[All, 2]]];
l2

{{{"a"}, {1, 2, 3, 4, 5}}, {{"b"}, {6, 7, 8, 9, 10}}}

l3 = MapAt[List, l, {All, 1}];
l3 = MapAt[ToExpression@StringReplace[#, {"[" -> "{", "]" -> "}"}] &, l3, {All, 2}];
l3

{{{"a"}, {1, 2, 3, 4, 5}}, {{"b"}, {6, 7, 8, 9, 10}}}

user1066 · Accepted Answer · 2019-07-17 12:40:04Z

4

{{#1}, ToExpression@StringSplit[#2,"["|"]"|","]}&@@@l

alternatively, using regex:

{{#1}, ToExpression@StringSplit[#2,RegularExpression["\W{1}"]]}&@@@l

{{{a}, {1, 2, 3, 4, 5}}, {{b}, {6, 7, 8, 9, 10}}}

answered Jul 17, 2019 at 12:40

user1066

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3 Answers 3