I'm trying to export a Julia dataframe into a CSV and it contains nothing values. To simiplify let's say I have the following dataframe:
using DataFrames, CSV
df = DataFrame(A = [nothing,2,3], B = [4,5,nothing])
When I try to export, I get the following error:
df |> CSV.write("df.csv")
ArgumentError: `nothing` should not be printed; use `show`, `repr`, or custom output instead.
Should I convert the nothing values to something else like missing? If so, how would I code this?
You can use something function to convert nothing to whatever you want (e.g. missing) like this:
something.(df, missing) |> CSV.write("aaa.txt")
The current reasoning behind the design not to support nothing when writing a CSV file is given here.
I prefer the syntax of the CSV transform argument:
CSV.write("filename.csv", df, transform=(col, val) -> something(val, missing))
From the CSV.write documentation
Posting this as a separate answer, hopefully to distinguish comments and gather clarifications if I am missing something important.