This is machine translation

Translated by Microsoft
Mouseover text to see original. Click the button below to return to the English verison of the page.

Note: This page has been translated by MathWorks. Please click here
To view all translated materals including this page, select Japan from the country navigator on the bottom of this page.


Latitudes and longitudes of nonzero data grid elements


[lat,lon] = findm(Z,R)
[lat,lon] = findm(latz,lonz,Z)
[lat,lon,val] = findm(...)
mat = findm(...)


[lat,lon] = findm(Z,R) computes the latitudes and longitudes of the nonzero elements of a regular data grid, Z. R can be a geographic raster reference object, a referencing vector, or a referencing matrix.

If R is a geographic raster reference object, its RasterSize property must be consistent with size(Z).

If R is a referencing vector, it must be a 1-by-3 with elements:

[cells/degree northern_latitude_limit western_longitude_limit]

If R is a referencing matrix, it must be 3-by-2 and transform raster row and column indices to or from geographic coordinates according to:

[lon lat] = [row col 1] * R

If R is a referencing matrix, it must define a (non-rotational, non-skewed) relationship in which each column of the data grid falls along a meridian and each row falls along a parallel. Nearest-neighbor interpolation is used by default. NaN is returned for points outside the grid limits or for which lat or lon contain NaN. All angles are in units of degrees.

[lat,lon] = findm(latz,lonz,Z) returns the latitudes and longitudes of the nonzero elements of a geolocated data grid Z, which is an M-by-N logical or numeric array. Typically latz and lonz are M-by-N latitude-longitude arrays, but latz may be a latitude vector of length M and lonz may be a longitude vector of length N.

[lat,lon,val] = findm(...) returns the values of the nonzero elements of Z, in addition to their locations.

mat = findm(...) returns a single output, where mat = [lat lon].

This function works in two modes: with a regular data grid and with a geolocated data grid.


The data grid can be the result of a logical operation. For instance, you can find all locations with elevations greater than 5500 meters.

load topo
[lat, lon] = findm((topo>5500),topolegend);
[lat lon]

ans =
   34.5000   79.5000
   34.5000   80.5000
   30.5000   84.5000
   28.5000   86.5000

These points are in the Himalayas. Find the grid values at these locations with setpostn:

heights = topo(setpostn(topo,topolegend,lat,lon))

heights =
Use a regular data grid to retrieve the elevations from setpostn.

See Also

Introduced before R2006a

Was this topic helpful?