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    <p>What i can decrypt from your question is that you have an 11 x 19 array and the numbers comprising this array appear to be real numbers in the range 0 &lt;= x &lt;= 1 (obviously neither assumption is critical to the answer).</p> <p>Below is the code to create a heatmap of your array such that the smallest values are lighter and the larger values are darker shades of grey (eg, '0' is white, and '1' is black).</p> <p>So first, create an array <em>identical in shape and value range</em> to yours:</p> <pre><code>import numpy as NP M = NP.random.rand(209).reshape(11, 19) M.shape # returns: (11, 19) # if the array returned from your call to 'genfromtxt' # is not 11 x 19, # then you need to reshape it so that it is, # use, e.g., 'data.reshape(11, 19)' from matplotlib import pyplot as PLT from matplotlib import cm as CM fig = PLT.figure() ax1 = fig.add_subplot(111) </code></pre> <p><strong>gray_r</strong> refers to a particular matplotlib <em>color map</em>--ie, creates a look-up table that maps each of the cell values in your 2D array to a cell color/hue (put another way: <em>color maps</em> just maps a palette to data;</p> <p>the <strong>r</strong> just refers to <em>reverse</em>; i pefer this mapping because it seems more intuitive to me--ie, white is mapped to 0 and larger values are mapped to darker shades of gray;</p> <p>the available colormaps are in the module <strong>cm</strong>; <strong><em>dir(matplotlib.cm)</em></strong> to get a list of the installed colormaps (there are dozens); the <a href="http://matplotlib.org/examples/color/colormaps_reference.html" rel="nofollow noreferrer">Matplotlib Site</a> has an excellent visual display of them (as a set of matplotlib plots of course).</p> <pre><code># select the color map by calling get_cmap and passing in a registered colormap # and an integer value for _lut_ which is just the number of different colors desired cmap = CM.get_cmap('gray_r', 10) # map the colors/shades to your data ax1.imshow(M, interpolation="nearest", cmap=cmap) # plot it PLT.show() </code></pre>
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    1. POdraw csv file data as a heatmap using numpy and matplotlib
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    1. COThanks for the reply. I can get the plot easily with random number, however I can't get my csv file to plot. first it refuses to reshape. I have NaNs there so I tried masking but that failed too. Also, I had to delete the header and first column, is there a way to leave them and get labels for the axes? I've edited the original question to include an excerpt of the csv file. many thanks.
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    2. COShould `A2` be replaced by `M`? It seems that A2 has not been properly defined in this example
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