# R Tip: Use Slices

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`R`

has a very powerful array slicing ability that allows for some very slick data processing.

Suppose we have a `data.frame`

“`d`

“, and for every row where `d$n_observations < 5`

we wish to “`NA`

-out” some other columns (mark them as not yet reliably available). Using slicing techniques this can be done quite quickly as follows.

library("wrapr") d[d$n_observations < 5, qc(mean_cost, mean_revenue, mean_duration)] <- NA

(For “`qc()`

” please see R Tip: Use qc() For Fast Legible Quoting.)

The above notation is very convenient, compact, and powerful. We are adding this as operator to our `rquery`

query generator as `assign_slice()`

(and a related method for directly dealing with `NA`

/`NULL`

).

To

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