mask
Syntax
mask(X, Y)
Arguments
X is a scalar/vector/matrix.
Y is a conditional expression that generates true or false.
Details
Apply Y on each element of X. If the result is false, keep the element; if the result is true, change it to NULL. The result is of the same length as X.
Examples
$ x=1..10
$ mask(x, x>6);
[1,2,3,4,5,6,,,,]
$ m=matrix(1 2 3, 4 5 6, 7 8 9);
$ m;
#0 |
#1 |
#2 |
---|---|---|
1 |
4 |
7 |
2 |
5 |
8 |
3 |
6 |
9 |
$ mask(m, m<6);
#0 |
#1 |
#2 |
---|---|---|
7 |
||
8 |
||
6 |
9 |