vector

Create

Action	Code	Details
Define vector	c(1, 2, 3)
Define with n repeated values v	rep(v, n)
Define with n repeated values v	rep_len(v, n)
Zeros, length n	numeric(n)
NaNs, length n	NaN[1:n]
Sequence from a to b	seq(a, b)
Sequence between a to b of length n	seq(a, b, length.out=n)

Test

Action	Code	Details
Is vector	is.vector(x) && is.atomic(x)	is.vector() returns true for lists as well!
Is empty	length(x) == 0
Contains value v	v %in% x
Contains NA value(s)	anyNA(x)
Contains each of the values in vector v	all(v %in% x)
Does not contain value v	!(v %in% x)

Extract

Action	Code	Details
Length	length(x)
First element	x[1]
Last element	data.table::last(x)
Last element	tail(x, 1)

Aggregate

Action	Code	Details
Sum elements	sum(x)
Mean of elements	mean(x)
Mode	table(x) %>% sort() %>% names() %>% last()
Mode of positive integers 1:K	tabulate(x) %>% which.max()
Compute function per group, as list	tapply(x, INDEX = rep_len(1:2, length(x)), mean)	Outputs a list with the results per group

Indexing

Action	Code	Details
TRUE values	which(x)
FALSE values	which(!x)
Index of smallest value	which.min(x)
Index of largest value	which.max(x)

Derive

Order

Action	Code	Details
Sort descending	sort(x)
Reverse	rev(x)
Shuffle	sample(x)

Map

Element-wise operations

Action	Code	Details
If-else with constant results	ifelse(x == TRUE, 1, 0)
If-else with element-specific results	ifelse(x, seq(-1, -100, by=-1), 1:100)
Replace NAs by zeros	ifelse(is.na(x), 0, x)
Replace specific values by zeros	ifelse(x %in% values, 0, x)
Replace elements at index with given values	replace(x, c(2, 4), c(NA, Inf))
Order by value, breaking ties with further args	order(x)
Ranking, with ties option	rank(x, ties='first')
Clip values below a	pmin(x, a)
Clip values above b	pmax(x, b)
Find pairwise min between two vectors	pmin(x, y)
Find pairwise max between two vectors	pmax(x, y)
Discretize values into bin number	findInterval(1:4, c(0, 2, 4))
Discretize values into n levels	cut(x, n)
Discretize values in specified intervals	cut(x, breaks)
Linear interpolation	approxfun(x, method='linear')(x2)
Spline interpolation	splinefun(x)(x2)
Smoothing spline interpolation	smooth.spline(x) %>% predict(x2)

Grow

Action	Code	Details
Repeat vector n times	rep(x, n)
Repeat vector up to length n	rep_len(x, n)

Shrink

Action	Code	Details
Exclude NA	na.exclude(x)
Exclude NA	x[!is.na(x)]
Exclude NA	Filter(Negate(is.na), x)
Exclude non-finite values	x[is.finite(x)]
Exclude non-finite values	Filter(is.finite, x)
Lagged difference	diff(x)
Sample n elements	sample(x, n)

Convert

Action	Code	Details
Split into a list of vectors, according to a grouping vector	split(x, g)	Can be undone by unsplit(y, g)
Running-length encoding	rle(x)