Reshape a CSV by pairing all fields but one named 'date'

[NikosAlexandris]

I am recording this here as a future reference for me, and perhaps someone else. I've had a hard time to get a regular expression to match all field names but the one named date.

I have a series of fields like date, i1, i2, j1, j2, k1, k2. Then, I define PAIRS=i1,i2,j1,j2,k1,k2 which I want to correlate like

mlr.go --csv cat input.csv |mlr.go reshape -i "$PAIRS" -o covariables,correlation

And this works fine.

Consider that the fields other than date are many more. Hence, I would like to get this running via a regular expression by matching all other field names. Before finally understanding the simple syntax required,

mlr.go reshape -r '[^date]' -o covariables,correlation

I was trying many things like

-r '!(^date)'
-r '!^date'
-r '!date'
-r '?!date'
-r '[^d]'
-r '[^d]*'
-r '[^da*]*'
-r '[^date*]'
-r '[^date]*'
-r '^((?!date).)*$'
-r '^((?!date).)*'
-r '^(?!date)(.*)'
-r '^(?!date).)*'
-r '^(?!date).*$'
-r '^(?!date).*'
-r '^?!date.*$'
-r '^[?!date].*'
-r '^\(\(?!date\).\)*$'
-r '^date'
-r '^date*'
-r [^date]*
-r ^date*
-r date*

😆

[aborruso]

If you asked right here, I had the answer ready for you🙃

[NikosAlexandris]

Learning process... :-)