Question

I have this code in MATLAB:

ext = [lat(end, :); lat; lat(1, :)];
lat = [ext(:, end) ext ext(:, 1)];

and I tried to do this in SciPy:

ext = sc.vstack([[lat[-1,:]], [lat], [lat[0,:]]])
lat = sc.vstack([[ext[:]], [ext], [ext[:,0]]])

but it gives me the errors:

ValueError: arrays must have same number of dimensions

and:

return _nx.concatenate(map(atleast_2d,tup),0) –> (in /usr/lib/pymodules… it’s the definition of vstack function)

Where am I going wrong?

Answer 1

You are stacking vertically in ext and horizontally in lat.

Try:

ext = sc.vstack([lat[-1,:], lat, lat[0,:]])
lat = sc.hstack([ext[:,-1], ext, ext[:,0]])

EDIT:

The code above will only work if lat is originally a matrix, rather than an array. If that’s not the case, you can convert by lat = sc.matrix(lat). Also note that I eliminated the extra square brackets in the argument to hstack and vstack.