R language Apply function family detailed

Apply	Apply Functions over Array Margins Use functions against column rows or columns	Apply (X, MARGIN, fun, ...)
Lapply	Apply a Function over a List or Vector Using functions on lists or vectors	Lapply (X, fun, ...)
Sapply	Apply a Function over a List or Vector Using functions on lists or vectors	Sapply (X, fun, ..., simplify = TRUE, use.) NAMES = TRUE)
Vapply	Apply a Function over a List or Vector Using functions on lists or vectors	Vapply (X, fun, fun. VALUE, ..., use. NAMES = TRUE)
Tapply	Apply a Function over a ragged Array Using functions for irregular arrays	Tapply (X, INDEX, fun = NULL, ..., simplify = TRUE)
Eapply	Apply a Function over Values in an environment Using functions for values in the environment	Eapply (env, fun, ..., all.names = FALSE, use.) NAMES = TRUE)
Mapply	Apply a Function to multiple List or Vector Arguments Use functions for multiple lists or vector parameters	Mapply (fun, ..., Moreargs = NULL, simplify = TRUE, use.) NAMES = TRUE)
Rapply	Recursively Apply a Function to a List Using functions to recursively generate lists	Rapply (object, F, classes = "any", Deflt = Null,how = C ("Unlist", "Replace", "List"), ...)

Apply {Base}

Use a function to generate a list of worth or arrays, vectors, by using an array or a dimension of the matrix.

Apply (X, MARGIN, fun, ...)

X array, including matrix

MARGIN 1 represents a matrix row, 2 represents a matrix column, or C (UP)

Cases:

>xxx<-matrix (1:20,ncol=4)

>apply (Xxx,1,mean)

[1] 8.5 9.5 10.5 11.5 12.5

>apply (Xxx,2,mean)

[1] 3 8 13 18

>xxx

[, 1] [, 2] [, 3] [, 4]

[1,] 1 6 11 16

[2,] 2 7 12 17

[3,] 3 8 13 18

[4,] 4 9 14 19

[5,] 5 10 15 20

lapply {Base}

Generate a list of values with the same number of elements by using a function on each element of X

Lapply (X, fun, ...)

x represents a vector or expression object, and the remaining objects are cast to list by as.list

Cases:

> x <-list (a = 1:10, beta = exp ( -3:3), logic = C (true,false,false,true))

> x

$a

[1] 1 2 3 4 5 6 7 8 9 10

$beta

[1] 0.04978707 0.13533528 0.36787944 1.00000000 2.71828183 7.38905610

[7] 20.08553692

$logic

[1] True false false true

> lapply (X,mean)

$a

[1] 5.5

$beta

[1] 4.535125

$logic

[1] 0.5

sapply {Base}

This is a user-friendly version and is a wrapper version of the Lapply function. The function returns a vector, a matrix, and, if simplify= "array", is converted to an array by the Simplify2array () function, if appropriate. Sapply (x, F, Simplify=false, use.) NAMES=FALSE) The returned value is consistent with lapply (X,F).

Sapply (X, fun, ..., simplify = TRUE, use.) NAMES = TRUE)

x represents a vector or expression object, and the remaining objects are cast to list by as.list

Simplify logical values or strings, if possible, the result should be reduced to vectors, matrices, or high-dimensional arrays. Must be named and cannot be abbreviated. The default value is true, and a vector or matrix will be returned if appropriate. If simplify= "Array", the result will return an array.

Use. NAMES the logical value, if true, and X is not named, the X is named.

Cases:

> sapply (k, Paste,use. Names=false,1:5,sep= "...")

[, 1]    [, 2] [, 3]

[1,] "A ... 1 "" B ... 1 "" C ... 1 "

[2,] "A ... 2 "" B ... 2 "" C ... 2 "

[3,] "A ... 3 "" B ... 3 "" C ... 3 "

[4,] "A ... 4 "" B ... 4 "" C ... 4 "

[5,] "A ... 5 "" B ... 5 "" C ... 5 "

> sapply (k, Paste,use. Names=true,1:5,sep= "...")

A b C

[1,] "A ... 1 "" B ... 1 "" C ... 1 "

[2,] "A ... 2 "" B ... 2 "" C ... 2 "

[3,] "A ... 3 "" B ... 3 "" C ... 3 "

[4,] "A ... 4 "" B ... 4 "" C ... 4 "

[5,] "A ... 5 "" B ... 5 "" C ... 5 "

> sapply (k, Paste,use. Names=true,1:5,sep= "...", simplyfy=true)

A b C

[1,] "A ... 1...TRUE "" B ... 1...TRUE "" C ... 1...TRUE "

[2,] "A ... 2...TRUE "" B ... 2...TRUE "" C ... 2...TRUE "

[3,] "A ... 3...TRUE "" B ... 3...TRUE "" C ... 3...TRUE "