Hi All,

We're looking at running a Monte Carlo simulation with our GRASS data, and one step I'd like to simplify is making histograms. Currently we use R, but given that our input rasters have millions of cells, it's time consuming. I was thinking that we might be able to use GRASS directly, since we're just doing many r.mapcalc calls.

I see histogram.c, and ideally I'd like to just roll a custom r.mapcalc which adds its output to a histogram function, then write it out at the end of the program. My C chops are poor, but I'm imagining something as simple (in Python) as:

hist = {}
values = [0.1, 0.1, 0.2, 3, 5, 3, 0.1, 0.2, 3, 0.1, 0.1]

for v in values:
    if hist.has_key(v):
        hist[v] += 1
    else:
        hist[v] = 1

What would be my best bet for creating this histogram? Is hacking up my own mapcalc function feasible?

thanks for the guidance,
Shaun Walbridge

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