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POmatplotlib.mlab.griddata very slow and returns array of nan when valid data is input
 

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  1. POmatplotlib.mlab.griddata very slow and returns array of nan when valid data is input
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    <p>I am trying to map an irregularly gridded dataset (raw satellite data) with associated latitudes and longitudes to a regularly gridded set of latitudes and longitudes given by <code>basemap.makegrid()</code>. I am using <code>matplotlib.mlab.griddata</code> with <code>mpl_toolkits.natgrid</code> installed. Below is a list of the variables being used as output by <code>whos</code> in ipython and some stats on the variables:</p> <pre><code>Variable Type Data/Info ------------------------------- datalat ndarray 666x1081: 719946 elems, type `float32`, 2879784 bytes (2 Mb) datalon ndarray 666x1081: 719946 elems, type `float32`, 2879784 bytes (2 Mb) gridlat ndarray 1200x1000: 1200000 elems, type `float64`, 9600000 bytes (9 Mb) gridlon ndarray 1200x1000: 1200000 elems, type `float64`, 9600000 bytes (9 Mb) var ndarray 666x1081: 719946 elems, type `float32`, 2879784 bytes (2 Mb) In [11]: var.min() Out[11]: -30.0 In [12]: var.max() Out[12]: 30.0 In [13]: datalat.min() Out[13]: 27.339874 In [14]: datalat.max() Out[14]: 47.05302 In [15]: datalon.min() Out[15]: -137.55658 In [16]: datalon.max() Out[16]: -108.41629 In [17]: gridlat.min() Out[17]: 30.394031556984299 In [18]: gridlat.max() Out[18]: 44.237140350357713 In [19]: gridlon.min() Out[19]: -136.17646180595321 In [20]: gridlon.max() Out[20]: -113.82353819404671 </code></pre> <p><code>datalat</code> and <code>datalon</code> are the orignal data coordinates</p> <p><code>gridlat</code> and <code>gridlon</code> are the coordinates to interpolate to</p> <p><code>var</code> contains the actual data</p> <p>Using these variables, when I call <code>griddata(datalon, datalat, var, gridlon, gridlat)</code> it has taken as long as 20 minutes to complete and returns an array of <code>nan</code>. From looking at the data, the latitudes and longitudes appear to be correct with the original coordinates overlapping a portion of the new area and a few data points lying outside of the new area. Does anyone have any suggestions? The nan values suggest that I'm doing something stupid...</p>
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      1. POmatplotlib.mlab.griddata very slow and returns array of nan when valid data is input
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    1. COWhat satellite? Is it a scanner or a staring FPA? What's the ground sample distance?
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      1. POmatplotlib.mlab.griddata very slow and returns array of nan when valid data is input
      1. USCarl F.
    2. COHeh, there's the fun part. I need to be capable of doing this for some 40+ different atmospheric sensors. Most of them are scaning sensors (conical, cross track, etc).
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