| newbie sees iterative solution, wants to know the IDL Way [message #61538] |
Sun, 20 July 2008 21:28 |
Tom Roche
Messages: 11
Registered: July 2008
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Junior Member |
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<best viewed in monospace font/>
From what I read, iteration is not the way to go with IDL. So I'm
wondering, how to translate the following iterative solution:
I'm reading netCDF data with dimensions={time, lat, lon}, from which I
want to get the "seasonality" such that, for each spacetime, I get the
proportion of the total over time at that point in space. E.g. if I
had input data for 4 space points (j,k) @ 2 time points (i):
(k=0) j=0 j=1
i=0: 0 1
i=1: 2 3
(k=1)
i=0: 4 5
i=1: 6 7
it would map to
0 1/4
1 3/4
2/5 5/12
3/5 7/12
My coding background is such that I quickly see an iterative solution
like
nTime=size of time dimension;
nLat=size of latitude dimension;
nLon=size of longitude dimension;
create array summing[nLat][nLon];
for (int i = 0; i < nTime; i++)
for (int j = 0; j < nLat; j++)
for (int k = 0; k < nLon; k++)
// gotta handle input=NaN
if (isNumber(input[i][j][k]))
summing[j][k] += input[i][j][k];
create array seasonality[nTime][nLat][nLon];
for (int i = 0; i < nTime; i++)
for (int j = 0; j < nLat; j++)
for (int k = 0; k < nLon; k++)
// gotta handle input=NaN, summing={0, NaN}
if (isNumber(input[i][j][k]) &&
isNumber(summing[j][k]) &&
(input[i][j][k] != 0))
seasonality[i][j][k] = input[i][j][k] / summing[j][k];
Is there a better, IDLer way?
TIA, Tom Roche <Tom_Roche@pobox.com>
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