showcols not defined in Julia

Question

I was working with a CSV file and I want to check for missing values in each column in that file using showcols but Julia Repl throws an error. Should I use any package for that

Answer 1

It seems that showcols used to be a function in DataFrames a very long time ago (I can find a mention of it in the docs for DataFrames v0.11 - the current release is v0.22).

Assuming that your data is indeed in a DataFrame, you can use describe to get summary statistics, including the number of missing values.

julia> using DataFrames

julia> df = DataFrame(rand(2, 3), :auto);

julia> describe(df)
3×7 DataFrame
 Row │ variable  mean      min       median    max       nmissing  eltype   
     │ Symbol    Float64   Float64   Float64   Float64   Int64     DataType 
─────┼──────────────────────────────────────────────────────────────────────
   1 │ x1        0.614285  0.301365  0.614285  0.927204         0  Float64
   2 │ x2        0.635276  0.588937  0.635276  0.681614         0  Float64
   3 │ x3        0.235452  0.231867  0.235452  0.239037         0  Float64

Also, for a DataFrame as well as for many other tables you can iterate over columns and check for missings by e.g. doing

julia> (sum ∘ (x -> ismissing.(x))).(eachcol(df))

3-element Vector{Int64}:
 0
 0
 0