Dear Julia Users,
I’m learning Julia with DataFrames.jl and see this one example df[!, :name] to get all column elements under :name, which shows the same result as df[:, :name]. My question is:
- What does the “!” mean in this context?
- What is the difference between these two?
Find answers to all your questions here:
or in write-up form here (especially rules 5 and 6):
: are the same. The difference is that
: (safer, slower) copies data and
! does not copy data (more error prone, but faster).
I typically recommend users to use
: unless they have a reason to use
That’s exactly what I’m looking for. I thought “!” is an commonly used matrix selector in Julia and forget to check it in DataFrames package. Great thanks!