How can I get the longest list in Julia dataframe?-CodePudding

Give a dataframe like this :

dataframe = DataFrame(col1 = rand(3), 
                      col2 = [['a'],['a','b','c'],['a','c']])

How can I get the longest list in col2?

I tried with :

dataframe[partialsortperm(dataframe.col2, 1, rev=true), :]

but It returns ['a','c'] instead of ['a','b','c].

CodePudding user response：

[EDIT] Actually, you want argmax:

julia> argmax(length, dataframe.col2)
3-element Vector{Char}:
 'a': ASCII/Unicode U 0061 (category Ll: Letter, lowercase)
 'b': ASCII/Unicode U 0062 (category Ll: Letter, lowercase)
 'c': ASCII/Unicode U 0063 (category Ll: Letter, lowercase)

[pre-EDIT answer below:]

I think you want to use findmax:

julia> findmax(length, dataframe.col2) # returns (max length, index)
(3, 2)

julia> dataframe.col2[findmax(length, dataframe.col2)[2]]
3-element Vector{Char}:
 'a': ASCII/Unicode U 0061 (category Ll: Letter, lowercase)
 'b': ASCII/Unicode U 0062 (category Ll: Letter, lowercase)
 'c': ASCII/Unicode U 0063 (category Ll: Letter, lowercase)