findIdx#

Purpose#

Returns the indices of elements where a condition is true.

idx = findIdx(cond)#

Parameters:: cond (Nx1 or 1xN vector) – boolean vector of 0s and 1s, typically the result of an element-wise comparison such as x .> 0. Both column vectors and row vectors are accepted.
Returns:: idx (Mx1 vector) – the row indices where cond is nonzero. If no elements are nonzero, a scalar missing value is returned.

x = { 3, -1, 5, -2, 7 };

idx = findIdx(x .> 0);

After the above code, idx will equal:

1
3
5

x = { 3, -1, 5, -2, 7 };

// Get indices where x is negative
idx = findIdx(x .< 0);

// Extract those elements
neg_vals = x[idx];

After the above code, neg_vals will equal:

-1
-2

Added in version 26.0.1.

findIdx() is equivalent to:

idx = selif(seqa(1, 1, rows(cond)), cond);

If you only need the matching values (not their indices), use selif() directly:

pos_vals = selif(x, x .> 0);