Adding DSL functions to to join field?

[aborruso]

Hi,
several times before running a join, I need to transform a field. In example I need to capitalize it.

It would be great to have something like the code below and be able to use mlr DSL functions.

mlr --csv join --ul -j fieldOne -l fieldOne -r 'uppercase(fieldTwo)' ...

What about it?

[aborruso]

@johnkerl ping :)

[johnkerl]

Hi @aborruso -- sorry for the delay.

My recommendation would be a 'decorate, join, undecorate' which also has the fancy name of Schwartzian transform -- a fancy way of adding: add a column using put; do the join; remove it using cut -x.

I think this would suffice ... and I hope so, since put/filter are already complex in their DSL, and join is already complex in its join logic ... if we can do this by leveraging each verb's strengths rather than adding one's complexities to the other, that would be nice ...

[aborruso]

Ok you are right.

Once again I have learned something

[trantor]

Ah, the good old Schwartzian transform... as a perler I much appreciate the reference 😄