dmap | R Documentation |
dmap()
is just like purrr::map()
but always returns a
data frame. In addition, it handles grouped or sliced data frames.
dmap(.d, .f, ...) dmap_at(.d, .at, .f, ...) dmap_if(.d, .p, .f, ...)
.d |
A data frame. |
.f |
A function, formula, or vector (not necessarily atomic). If a function, it is used as is. If a formula, e.g.
This syntax allows you to create very compact anonymous functions. If character vector, numeric vector, or list, it is
converted to an extractor function. Character vectors index by
name and numeric vectors index by position; use a list to index
by position and name at different levels. If a component is not
present, the value of |
... |
Additional arguments passed on to the mapped function. |
.at |
A character vector of names, positive numeric vector of
positions to include, or a negative numeric vector of positions to
exlude. Only those elements corresponding to |
.p |
A single predicate function, a formula describing such a
predicate function, or a logical vector of the same length as |
dmap_at()
and dmap_if()
recycle length 1 vectors to
the group sizes.
# dmap() always returns a data frame: dmap(mtcars, summary) # dmap() also supports sliced data frames: sliced_df <- mtcars[1:5] %>% slice_rows("cyl") sliced_df %>% dmap(mean) sliced_df %>% dmap(~ .x / max(.x)) # This is equivalent to the combination of by_slice() and dmap() # with 'rows' collation of results: sliced_df %>% by_slice(dmap, mean, .collate = "rows")
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