# [R] create a function with "subset" statement

JSHuang js.huang at protective.com
Fri Jan 30 03:34:41 CET 2015

```Hi,

The following is implemented with function named subsetAll.  It calls the
function subset1.  The input to subset1 is the matrix A and a vector
indicating the beginning and ending values for columns 1 and 2.  Input to
subsetAll is the matrix A and a matrix that is row bind from those vectors
constitute the conditions.

> subset1
function(A,v)
{
A[A[,1] %in% v[1]:v[2] & A[,2] %in% v[3]:v[4],]
}
> subsetAll
function(A,m)
{
v <- as.vector(m[1,])
result <- subset1(A,v)
if (dim(m)[1] > 1)
{
for (i in 2:dim(m)[1])
{
v <- as.vector(m[i,])
result <- rbind(result,subset1(A,v))
}
}
result
}
> A
a b           c
[1,] 1 1 -0.04160857
[2,] 1 2  0.75486670
[3,] 1 3 -0.21022257
[4,] 1 4 -1.02594314
[5,] 1 5 -1.91864901
[6,] 2 1  0.19760459
[7,] 2 2 -1.30046908
[8,] 2 3  0.30554275
[9,] 2 4 -0.41861494
[10,] 2 5  0.22763712
[11,] 3 1  1.20244853
[12,] 3 2  1.15425304
[13,] 3 3 -2.13727010
[14,] 3 4 -0.27288205
[15,] 3 5 -1.08974847
[16,] 4 1  0.44501360
[17,] 4 2 -2.79163479
[18,] 4 3 -0.26713804
[19,] 4 4  1.31392292
[20,] 4 5  1.75383175
> (mB <- rbind(c(1,2,1,2),c(3,3,1,1),c(4,4,1,4)))
[,1] [,2] [,3] [,4]
[1,]    1    2    1    2
[2,]    3    3    1    1
[3,]    4    4    1    4
> (B <- subsetAll(A,mB))
a b           c
[1,] 1 1 -0.04160857
[2,] 1 2  0.75486670
[3,] 2 1  0.19760459
[4,] 2 2 -1.30046908
[5,] 3 1  1.20244853
[6,] 4 1  0.44501360
[7,] 4 2 -2.79163479
[8,] 4 3 -0.26713804
[9,] 4 4  1.31392292
> (mC <- rbind(c(1,4,1,2)))
[,1] [,2] [,3] [,4]
[1,]    1    4    1    2
> (C <- subsetAll(A,mC))
a b           c
[1,] 1 1 -0.04160857
[2,] 1 2  0.75486670
[3,] 2 1  0.19760459
[4,] 2 2 -1.30046908
[5,] 3 1  1.20244853
[6,] 3 2  1.15425304
[7,] 4 1  0.44501360
[8,] 4 2 -2.79163479
> (mD <- rbind(c(1,2,1,3),c(3,3,1,2)))
[,1] [,2] [,3] [,4]
[1,]    1    2    1    3
[2,]    3    3    1    2
> (D <- subsetAll(A,mD))
a b           c
[1,] 1 1 -0.04160857
[2,] 1 2  0.75486670
[3,] 1 3 -0.21022257
[4,] 2 1  0.19760459
[5,] 2 2 -1.30046908
[6,] 2 3  0.30554275
[7,] 3 1  1.20244853
[8,] 3 2  1.15425304
>

--
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```