[Numpy-discussion] Optimize speed of for loop using numpy

[Robert Kern]

On Mon, Feb 25, 2008 at 8:32 PM, Trond Kristiansen <trond at unc.edu> wrote:
> Hi again.
>
>  I have attached the function that the FOR loop is part of as a python file.
>  What I am trying to do is to create a set of functions that will read the
>  output files (NetCDF) from running the ROMS model (ocean model). The output
>  file is organized in xi (x-direction), eta (y-direction), and s
>  (z-direction) where the s-values are vertical layers and not depth. This
>  particular function (z_slice) will find the closest upper and lower s-layer
>  for a given depth in meters (e.g. -100). Then values from the two selcted
>  layers will be interpolated to create a new layer at the selected depth
>  (-100). The problem is that the s-layers follow the bathymetry and a
>  particular s-layer will therefore sometimes be above and sometimes below the
>  selected depth that we want to interpolate to. That's why I need a quick
>  script that searches all of the layers and find the upper and lower layers
>  for a given depth value (which is negative). The z_r is a 3D array
>  (s,eta,xi) that is created using the netcdf module.

Ah, that makes things clearer. You should be able to remove the
innermost k-loop by using searchsorted().

-- 
Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco