Finding an array of numbers in an array

Hi

I have the attached coords_17 array, which is 2092 x 3 dimensional. Within this array, I want to find say the row which contains the coordinates [44, -30, 54]. However, the following commands fails somehow:

find(coords_17 == [44, -30, 54])

How can I find the relevant coordinates correctly? Many thanks

Answer 1

[Star Strider]

I would use the ismember (link) function.

Try this:

target = [44, -30, 54];
Lidx = ismember(coords_17, target, 'rows');
row_number = find(Lidx)

row_number =
     2

[MiauMiau]

Thanks! What is the reason it does not work with a simple "find"?

[Star Strider]

Correct.

Using ismember (or ismembertol if you are matching non-integers) first, and then using find is much more efficient.

It might be possible with find, however that would likely require matching each column and then searching for matching row indices.

[MiauMiau]

thx

[Star Strider]

As always, my pleasure!