# Minimum and maximum by column in a datafram

Hello,

I’m a beginner with Julia.

I’ve got a dataframe called data that i converted in an array of floats.

``````data_temp = deepcopy(data)
array=Matrix(data_temp[:,2:size(data_temp,2)])
df=Array{Float64}(array)
``````

Now, i want to extract from the array df (10 rows and 5 columns)

• a vector{Float64} including the smallest values for the 3 first columns and the highest values for the 2 last columns
• a vector{Float64} including the highest values for the 3 first columns and the smallest values for the 2 last columns

I don’t know how to do it.

You don’t need a Matrix at all:

``````vec_1 = [minimum.(eachcol(df[!, 1:3]); maximum.(eachcol(df[!, 4:5]))]
``````

I’ve tried:

``````bo=[minimum(df[:,1:3],dims=1);maximum(df[:,4:5],dims=1)]
``````

But it doesn’t work.
Why ?

``````minimum(df[:,1:3],dims=1)
``````

gives a `1x3` matrix, which is not a vector. Maybe you want to `collect` that output so you can `vcat` them.

The error is pretty self-explanatory imo. Make sure you read the error messages and debug piece by piece.

ok but how can i concatenate the 1x3 matrix and the 1x2 matrix ?

``````bo=vcat(minimum(df[:,1:3],dims=1),maximum(df[:,4:5],dims=1))
``````

doesn’t work

The `vcat` here is exactly the same as `;` above.

You can use `hcat` or, as I wrote above, use `collect`