Apply a function over elements of a vector.
Usage
vap(x, f, ...)
vapi(x, f, ...)
vap2(x, y, f, ...)
vap3(x, y, z, f, ...)
vapp(p, f, ...)
vap_lgl(x, f, ...)
vap_int(x, f, ...)
vap_dbl(x, f, ...)
vap_chr(x, f, ...)
vap_raw(x, f, ...)
vap_cpl(x, f, ...)
vap_date(x, f, ...)
vap_dttm(x, f, ...)
vapi_lgl(x, f, ...)
vapi_int(x, f, ...)
vapi_dbl(x, f, ...)
vapi_chr(x, f, ...)
vapi_raw(x, f, ...)
vapi_cpl(x, f, ...)
vapi_date(x, f, ...)
vapi_dttm(x, f, ...)
vap2_lgl(x, y, f, ...)
vap2_int(x, y, f, ...)
vap2_dbl(x, y, f, ...)
vap2_chr(x, y, f, ...)
vap2_raw(x, y, f, ...)
vap2_cpl(x, y, f, ...)
vap2_date(x, y, f, ...)
vap2_dttm(x, y, f, ...)
vap3_lgl(x, y, z, f, ...)
vap3_int(x, y, z, f, ...)
vap3_dbl(x, y, z, f, ...)
vap3_chr(x, y, z, f, ...)
vap3_raw(x, y, z, f, ...)
vap3_cpl(x, y, z, f, ...)
vap3_date(x, y, z, f, ...)
vap3_dttm(x, y, z, f, ...)
vapp_lgl(p, f, ...)
vapp_int(p, f, ...)
vapp_dbl(p, f, ...)
vapp_chr(p, f, ...)
vapp_raw(p, f, ...)
vapp_cpl(p, f, ...)
vapp_date(p, f, ...)
vapp_dttm(p, f, ...)
with_vap_progress(expr)
with_vap_handlers(expr)Value
For vap(), vapi(), returns a list with length of x. For
vap2(), vap3(), and vap(), return length is determined by how ...
is recycled inside mapply().
All have type variants (e.g., vap_chr(), vapi_int(), vap3_dbl())
which return a vector of the corresponding class, with the same length of
x, or following the same recycling rules as mapply() for multiple
inputs. These returns are coerced, rather than checked, and may result
in unexpected outputs. Likely, warnings or errors will be signaled
accordingly.
with_vap_progress() sets an option vap.progress to TRUE for the
duration of expr, which causes a progress bar to be displayed for any
vap* calls inside expr.
with_vap_handlers() sets an options(vap.indexed_errors = TRUE) for the
duration of expr, which causes errors inside vap calls to include the
index at which the error occurred.
Details
Like lapply(), mapply(), and family, the vap functions provide
a means of applying a function to each element of a vector, and
controlling return types. The vap family provides extra tools and
controls, as well as date outputs (i.e., _date, _dttm variants that
work with Date and POSIXct types).
vap()uses a singlexargumentvapi()uses a singlexargument and passes the names (when available, otherwise index) as the second argumentvap2(),vap3()use two and three arguments, respectivelyvapp()uses a pairlist of arguments
Extras
Two helper functions are provided to set options for a
progress bars (options(fuj.vap.progress)) and reporting an index during
and error (options(fuj.vap.index_error)). Two wrapper functions are
provided: with_vap_progress() and with_vap_handlers(), respectively;
the latter may include other handlers in the future. These are not turned
on by default (or rather, the option settings are set to FALSE within
{fuj}) as they incur some additional overhead.
Examples
fruits <- c("apple", "banana", "pear")
vap(fruits, toupper)
#> [[1]]
#> [1] "APPLE"
#>
#> [[2]]
#> [1] "BANANA"
#>
#> [[3]]
#> [1] "PEAR"
#>
vapi(fruits, function(x, i) paste0(i, ": ", toupper(x)))
#> [[1]]
#> [1] "1: APPLE"
#>
#> [[2]]
#> [1] "2: BANANA"
#>
#> [[3]]
#> [1] "3: PEAR"
#>
vap_int(set_names(month.name, month.abb), nchar)
#> Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
#> 7 8 5 5 3 4 4 6 9 7 8 8
vap2_dbl(1:5, 6:10, `+`)
#> [1] 7 9 11 13 15
vapp_int(list(x = 1:5, y = 6:10, z = 11:15), sum)
#> [1] 18 21 24 27 30
# return type is coerced:
vap_int(1:5, paste0, "9") # character -> integer
#> [1] 19 29 39 49 59
vap_date(month.name, nchar) # integer -> Date
#> [1] "1970-01-08" "1970-01-09" "1970-01-06" "1970-01-06" "1970-01-04"
#> [6] "1970-01-05" "1970-01-05" "1970-01-07" "1970-01-10" "1970-01-08"
#> [11] "1970-01-09" "1970-01-09"
# when f is a character or number, subsetting is performed
x <- list(list(a = 1, b = 3), list(a = 2, b = 4))
vap_int(x, "a")
#> [1] 1 2
vap_int(x, 2)
#> [1] 3 4
# wrap in [with_vap_progress()] to show a progress bar
invisible(
with_vap_progress(
vap(1:10 / 20, Sys.sleep)
)
)
#>
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# wrap in [with_vap_handlers()] to report index on error
try(
with_vap_handlers(
vap(10:1, function(x) if (x == 3) stop("bad"))
)
)
#> Error in vap(10:1, function(x) if (x == 3) stop("bad")) :
#> error at index: 8:
#> bad