find

find indices of boolean vector or matrix true elements

Calling Sequence

[ii]=find(x [,nmax])
[i1,i2,..]=find(x [,nmax])

Arguments

:x may be a boolean vector, a boolean matrix, a boolean hypermatrix, a

“standard” matrix or hypermatrix

: :nmax an integer giving the maximum number of indices to return. The

default value is -1 which stands for “all”. This option can be used for efficiency, to avoid searching all indices.

: :ii, i1, i2, .. integer vectors of indices or empty matrices :

Description

If x is a boolean matrix,

ii=find(x) returns the vector of indices i for which x(i) is “true”. If no true element found find returns an empty matrix.

[i1,i2,..]=find(x) returns vectors of indices i1 (for rows) and i2 (for columns),.. such that x(i1(n),i2(n),..) is “true”. If no true element found find returns empty matrices in i1, i2, ...

if x is a standard matrix or hypermatrix find(x) is interpreted as find(x<>0)

find([]) returns []

Examples

beers=["Desperados", "Leffe", "Kronenbourg", "Heineken"];
find(beers=="Leffe") // OK
find(beers=="1664") // KO
find(beers=="Foster") // KO
beers=[beers, "Foster"]
find(beers=="Foster") // OK

A=`rand`_(1,20);
w=find(A<0.4)
A(w)
w=find(A>100)

B=`rand`_(1,20);
w=find(B<0.4,2) //at most 2 returned values

H=`rand`_(4,3,5); //an hypermatrix
[i,j,k]=find(H>0.9)

H(i(1),j(1),k(1))

See Also

• boolean Scilab Objects, boolean variables and operators & | ~
• extraction matrix and list entry extraction
• insertion partial variable assignation or modification
• vectorfind finds in a matrix rows or columns matching a vector