Minimum and maximum by column in a datafram

General Usage
,
1

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.

Thanks in advance for your help

2

You don’t need a Matrix at all:

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

I’ve tried:

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

But it doesn’t work.
Why ?

4 
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.

5

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

6

The vcat here is exactly the same as ; above.

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

Please read the responses carefully.

7

You are right !
Sorry…and thanks a lot !