Programmer Guide/Command Reference/EVAL/vsubn: Difference between revisions
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{{DISPLAYTITLE:{{SUBPAGENAME}}}} | {{DISPLAYTITLE:{{SUBPAGENAME}}}} | ||
Extract rows from a vector or matrix. | Extract rows from a vector or matrix. | ||
;Usage: '''<code><var> | ;Usage: '''<code>vsubn(<var>x</var> {, <var>o</var> {, <var>n</var>}})</code>''' | ||
:;<var>x</var>: source vector or matrix | :;<var>x</var>: source vector or matrix | ||
:;<var>o</var>: offset, 0 <= ''o'' < <code>nrow(''x'')</code> (default=0) | :;<var>o</var>: offset, 0 <= ''o'' < <code>nrow(''x'')</code> (default=0) | ||
Revision as of 09:10, 6 April 2011
Extract rows from a vector or matrix.
- Usage
vsubn(x {, o {, n}})- x
- source vector or matrix
- o
- offset, 0 <= o <
nrow(x)(default=0) - n
- length, n > 0 and o+n <=
nrow(x)(default=nrow(x)-o
- Result
- A numerical object with
ncol(x)columns and n rows, consisting of the rows o to o+n-1 of the argument x. - See also
- vsubc, select, vv
Example:
#a := eval vv(1,2,3,4,5)
#b := eval vmcol($#a, vv(5,4,3,2,1))
#c := vsubn($#a,3)
// -> vector: $#c = { 4 , 5 }
#d := eval vsubn($#b, 1 , 3)
// -> matrix: $#d[*,0] = { 2 , 3 , 4 }, $#d[*,1] = { 4 , 3 , 2 }
#e := eval vsubn($#a, 2, 1)
// -> scalar: $#e = 2, this is equivalent to $#a[2]
#f := eval vsubn($#b, 2, 1)
// -> vector (!!): $#f = { 3 , 3 }, this is equivalent to $#b[2,*]
