Chapter 21 R-like functions

Here is a list of Rcpp functions similar to R functions.

Also, if you can guarantee that NA is not included in the vector given to these functions, you can use noNA() to mark the vector. Then the functions below no longer checks for NA, so the calculation may speed up.

NumericVector res = mean(noNA(v));

21.1 List of R-like functions

• Vector related functions
• String related functions
• Functions related to finding values
• Functions related to duplicated values
• Functions related to set operation
• Functions related to maximum and minimum values
• Functions related to summaries
• Functions related to rounding values
• Functions related to math
• Functions related to logical values
• Functions related to NA Inf NaN
• apply functions
• cbind function

21.1.1 Vector related functions

head(v, n)

Returns a vector of n elements from the first element of the vector v.

tail(v, n)

Returns a vector of last n elements from the last element of vector v.

rev(v)

Returns a vector that elements of vector v are arranged in reverse order.

rep(x, n)

Returns a vector that x is repeated n times. x can be a scalar or vector.

rep_each(v, n)

Returns a vector that each elements of vector v are repeated n times.

rep_len(v, n)

Returns a vector that the vector v is repeated until the length of the vector becomes n.

seq(start, end)

Returns a vector of consecutive integers from start to end.

seq_along(v)

Returns a vector of consecutive integers from 1 to the number of elements of vector v

seq_len(n)

Returns a vector of consecutive integers from 1 to n

diff(v)

Returns a vector that computed v[i + 1] - v[i] for each element i excluding the last element of the vector v.

21.1.2 String related functions

collapse(v)

Returns a string concatenated with each element of the CharacterVector v as String type.

21.1.3 Finding values

match(v, table)

Returns an integer vector containing the R style numerical index (starting from 1) of the element of vector table that match value to each elements of vector x. Namely、if you execute res = match(v, table);, then it will be res[i] == j+1 where j equals to minimum j satisfying v[i] == table[j]

self_match(v)

Synonymous with passing the same vector to match (v, table).

which_max(v)

Returns the numerical index of the largest element of the vector v.

which_min(v)

Returns the numerical index of the smallest element of the vector v.

21.1.4 Duplicated values

duplicated(v)

Returns a vector containing 1 if the value of each element of vector v exists in the previous element, containing 0 if not.

unique(v)

Returns a vector that eliminates the duplication of the element value from the vector v.

sort_unique(v)

Returns a vector that eliminates the duplication of the element value from the vector v and sorts the values in ascending order.

21.1.5 Set operation

setdiff(v1,v2)

Returns a vector obtained by subtracting the value of the unique element of the vector v2 from the unique element of the vector v1.

setequal(v1,v2)

Returns true if the unique element of vector v1 is equal to the unique element of vector v2.

intersect(v1,v2)

Returns a vector containing elements contained in both the unique element of vector v1 and the unique element of vector v2.

union_(v1,v2)

Return vector which eliminated value duplication after combining elements of vector v1 and vector v2.

21.1.6 Functions related to maximum and minimum values

min(v)

Returns the minimum value of the vector v.

max(v)

Returns the maximum value of the vector v.

cummin(v)

Returns the cumulative minimum elements of vector v

cummax(v)

Returns the cumulative maximum elements of vector v

pmin(v1,v2)

Compares the corresponding elements of vectors v1 and v2, and return a vector containing the smaller elements.

pmax(v1,v2)

Compares the corresponding elements of vectors v1 and v2, and return a vector containing the larger elements.

range(v)

Returns a vector consisting of the minimum and maximum values of vector v.

clamp(min, v, max)

Returns a vector that the elements of vector v smaller than min is replaced with min and the elements larger than max is replaced with max.

21.1.7 Functions related to summaries

sum(v)

Returns the sum of the elements of vector v.

mean(v)

Returns the arithmetic mean of the elements of vector v.

median(v)

Returns the median value of the elements of vector v.

sd(v)

Returns the standard deviation of the elements of vector v.

var(v)

Returns the variance of the elements of vector v.

cumsum(v)

Returns the cumulative sum of the elements of vector v

cumprod(v)

Returns the cumulative product of the elements of vector v

table(v)

Returns a named integer vector that counts the number of elements for each unique element of vector v.

21.1.8 Functions related to rounding values

floor(v)

Returns a vector containing the largest integer not greater than each element of vector v.

ceil(v)

Returns a vector containing the largest integer not smaller than each element of vector v.

ceiling(v)

Synonymous with ceil().

round(v, digits)

Returns a vector obtained by rounding each element of the vector v with the number of significant figure digits.

trunc(v)

Returns a vector with rounded down decimal places.

21.1.9 Functions related to math

sign(v)

Returns a vector with the signs of the corresponding elements of v (the sign of a real number is 1, 0, or -1 if the number is positive, zero, or negative, respectively).

abs(v)

Returns a vector containing the absolute value of each element of vector v.

pow(v, n)

Returns a vector by raising each element of the vector v to the nth power.

sqrt(v)

Returns a vector containing square root of each element of vector v.

exp(v)

Returns a vector by raising Napier number (e) to the power of value of each element of the vector v.

expm1(v)

Synonymous with exp(v) - 1

log(v)

Returns a vector containing the natural logarithmic of each element of vector v.

log10(v)

Returns a vector containing the common logarithmic of each element of vector v.

log1p(v)

Synonymous with log(v+1)

sin(v)

Returns a vector containing sine of each element of vector v.

sinh(v)

Returns a vector containing hyperbolic sine of each element of vector v.

cos(v)

Returns a vector containing cosine of each element of vector v.

cosh(v)

Returns a vector containing hyperbolic cosine of each element of vector v.

tan(v)

Returns a vector containing tangent of each element of vector v.

tanh(v)

Returns a vector containing hyperbolic tangent of each element of vector v.

acos(v)

Returns a vector containing arccosine of each element of vector v.

asin(v)

Returns a vector containing arcsine of each element of vector v.

atan(v)

Returns a vector containing arctangent of each element of vector v.

gamma(v)

Returns a vector obtained by transforming each element of vector v with the gamma function.

lgamma(v)

Synonymous with log(gamma(v))

digamma(v)

Returns a vector obtained by transforming each element of vector v with the first derivative function of lgamma().

trigamma(v)

Returns a vector obtained by transforming each element of vector v with the second derivative function of lgamma().

tetragamma(v)

Returns a vector obtained by transforming each element of vector v with the third derivative function of lgamma().

pentagamma(v)

Returns a vector obtained by transforming each element of vector v with the fourth derivative function of lgamma().

psigamma(v, deriv)

Returns a vector obtained by transforming each element of vector v with the deriv-th derivative function of lgamma().

factrial(v)

Returns a vector containing the factorial of the each element of vector v.

lfactorial(v)

Synonymous with log(factrial(v))

choose(vn, vk)

Returns a vector obtained by calculating binomial coefficients using the corresponding elements of real vector vn and integer vector vk.

lchoose(vn, vk)

Synonymous with log(choose(vn, vk))

beta(va, vb)

Returns a vector obtained by calculating the value of the beta function using the corresponding elements of vectors va and vb.

lbeta(va, vb)

Synonymous with log(beta(va, vb))

21.1.10 Functions related to logical values

all(v)

Receives a LogicalVector v and returns SingleLogicalResult type meaningTRUE when all of elements are TRUE.

any(v)

Receives a LogicalVector v and returns SingleLogicalResult type meaningTRUE when any of elements are TRUE.

is_true(x)

Receives a return value of all() or any() and returns bool type true if it means TRUE.

is_false(x)

Receives a return value of all() or any() and returns bool type true if it means FALSE.

is_na(x)

Receives a return value of all() or any() and returns bool type true if it means NA.

ifelse(v, x1, x2)

Receives the LogicalVector v, and returns a vector containing the corresponding element of x1 or x2 when the element of v is TRUE or FALSE, respectively. Although x1 and x2 can be vectors or scalars, the length of the vector needs to be equal to v.

21.1.11 Functions related to NA Inf NaN

na_omit(v)

Returns a vector which deleted NA from vector v.

is_finite(v)

Returns a LogicalVector containing TRUE if corresponding elements of vector v is not Inf nor -Inf nor NA.

is_infinite(v)

Returns a LogicalVector containing TRUE if corresponding elements of vector v is Inf or -Inf or NA.

is_na(v)

Returns a LogicalVector containing TRUE if corresponding elements of vector v is NA or NaN.

is_nan(v)

Returns a LogicalVector containing TRUE if corresponding elements of vector v is NaN.

21.1.12 apply functions

lapply(x, fun)

Applies a C++ function fun to each element of the vector x and returns the result as List.

sapply(x, fun)

Applies a C++ function fun to each element of the vector x and returns the result as Vector.

mapply(x1, x2, fun2)

Applies a C++ function fun that receives two arguments to each corresponding elements of the vector x1 and x2 and returns the result as Vector.

mapply(x1, x2, x3, fun3)

Applies a C++ function fun that receives three arguments to each corresponding elements of the vector x1 and x2, x3 and returns the result as Vector.

21.1.13 cbind function

cbind(x1, x2,…)

Takes Vector or Matrix x1 and x2, ... and combine by columns. And returns the result as Matrix or DataFrame. You can pass up to 50 arguments.

21.1.14 sampling

Vector sample(Vector x, int size, replace = false, probs = R_NilValue)

As with the sample function in R, this function takes a sample from a vector x.

• x : a vector you want to draw a sample.
• size : sample size of returned vector.
• replace : should sampling be with replacement. default true.
• probs : a vector that specify probability weights to be drawn for each elements of vector x. default R_NilValue (same weight for all elements).

Vector<RTYPE> sample(const Vector<RTYPE>& x, int size, bool replace = false, sugar::probs_t probs = R_NilValue)

sample(n, size, replace = TRUE, probs = NULL, one_based = TRUE)

As with the sample.int function in R.

Vector<INTSXP> sample(int n, int size, bool replace = false, sugar::probs_t probs = R_NilValue, bool one_based = true);