Hi all, My first post was removed (not sure why), so here is try number 2… I’m new to Julia and am stuck on a problem. I have a dataframe defined as follows: df = DataFrame((name=["S1","S2","S3","S4","S5"],Z1=[41,12,19,17,11],Z2=[13,28,29,99,41],Z3=[7,86,23,12,71],Z4=[4,13,23,11,19],Z5=[41,12,13…

This works, but there must be a better one than this: n_lowest(row::DataFrameRow,n::Integer) = row[[1; partialsortperm(Vector(row[2:end]), 1:n).+1]] n_lowest.(eachrow(df),3) This is specific to your case where you have a “name” column in the first position, so we need an ‘offset’ index [[1; and t…

A small variation that returns the names (NB: edited to select only the columns with names like “Z” + number): nlowest!(df,n) = df[!,:nlowest] = names.((df,), [ones(Int,n)] .+ partialsortperm.(Vector.(eachrow(select(df,r"Z\d+"))), (1:n,))) n=3 nlowest!(df,n) julia> df 5×8 DataFrame Row │ name …

[image] Snowy: My first post was removed (not sure why), so here is try number 2… [image] For each row, return n lowest column indexes or column names General Usage Hi all, New to Julia and seeking a little help. I am working with a dataframe and for each row, I wa…

Thanks! This probably gets as close to what I was originally trying to achieve. Question for both though… Why is this the case that I can only run the function once? If I run the following code: nlowest!(df,n) = df[!,:nlowest] = names.((df,), [ones(Int,n)] .+ partialsortperm.(Vector.(eachrow(df[:…

Because the function mutates your dataframe and the next time you run it it includes the new column with strings in it, which fails. The ! suffix of the function indicates that it mutates the dataframe, that’s a common convention for naming things in Julia.

A version that doesn’t change the original dataframe: nlowest(df,n) = names.((df,), [ones(Int,n)] .+ partialsortperm.(Vector.(eachrow(df[:,2:end])), (1:n,)))

[image] Snowy: Why is this the case that I can only run the function once? I have updated the function nlowest!() in my post above to fix this. Basically by selecting only the columns with names like “Z” + number, in order to perform the analysis.

Returning the n lowest values across columns in a dataframe

New to Julia

jd-foster June 1, 2022, 12:35am 4

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Returning the n lowest values across columns in a dataframe

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