Apply head() across each element in a list of vectors
heads(x, n = 6, ...)list of atomic vectors, assumed to be the same
atomic type.
integer maximum number of items to include from
each element in the list x. When n contains multiple
values, they are recycled to length(x) and applied to each
list element in order.
additional arguments are passed to utils::head().
list with at most n elements per vector.
Note that this function currently only operates on a list
of vectors. This function is notably faster than
lapply(x, head, n) because it operates on the entire
vector in one step.
Also the input n can be a vector so that each element in
the list has a specific number of items returned.
Other jam practical functions:
breakDensity(),
checkLightMode(),
check_pkg_installed(),
colNum2excelName(),
color_dither(),
diff_functions(),
exp2signed(),
fileInfo(),
fixYellow(),
getAxisLabel(),
handleArgsText(),
isFALSEV(),
isTRUEV(),
jamba,
jargs(),
kable_coloring(),
lldf(),
log2signed(),
make_html_styles(),
make_styles(),
match_unique(),
mergeAllXY(),
middle(),
minorLogTicks(),
newestFile(),
printDebugI(),
printDebug(),
renameColumn(),
rmInfinite(),
rmNAs(),
rmNA(),
rmNULL(),
sclass(),
sdim(),
setPrompt()
Other jam list functions:
cPasteSU(),
cPasteS(),
cPasteUnique(),
cPasteU(),
cPaste(),
jam_rapply(),
list2df(),
mergeAllXY(),
mixedSorts(),
rbindList(),
relist_named(),
rlengths(),
sclass(),
sdim(),
uniques(),
unnestList()
l <- list(a=1:10, b=2:5, c=NULL, d=1:100);
heads(l, 1);
#> $a
#> [1] 1
#>
#> $b
#> [1] 2
#>
#> $c
#> integer(0)
#>
#> $d
#> [1] 1
#>
heads(l, 2);
#> $a
#> [1] 1 2
#>
#> $b
#> [1] 2 3
#>
#> $c
#> integer(0)
#>
#> $d
#> [1] 1 2
#>
heads(l, n=c(2, 1, 3, 5))
#> $a
#> [1] 1 2
#>
#> $b
#> [1] 2
#>
#> $c
#> integer(0)
#>
#> $d
#> [1] 1 2 3 4 5
#>