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POReplace subarrays in numpy
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copied!<p>Given an array,</p> <pre><code>>>> n = 2 >>> a = numpy.array([[[1,1,1],[1,2,3],[1,3,4]]]*n) >>> a array([[[1, 1, 1], [1, 2, 3], [1, 3, 4]], [[1, 1, 1], [1, 2, 3], [1, 3, 4]]]) </code></pre> <p>I know that it's possible to replace values in it succinctly like so,</p> <pre><code>>>> a[a==2] = 0 >>> a array([[[1, 1, 1], [1, 0, 3], [1, 3, 4]], [[1, 1, 1], [1, 0, 3], [1, 3, 4]]]) </code></pre> <p>Is it possible to do the same for an entire row (last axis) in the array? I know that <code>a[a==[1,2,3]] = 11</code> will work and replace all the elements of the matching subarrays with 11, but I'd like to substitute a different subarray. My intuition tells me to write the following, but an error results,</p> <pre><code>>>> a[a==[1,2,3]] = [11,22,33] Traceback (most recent call last): File "<stdin>", line 1, in <module> ValueError: array is not broadcastable to correct shape </code></pre> <p>In summary, what I'd like to get is:</p> <pre><code>array([[[1, 1, 1], [11, 22, 33], [1, 3, 4]], [[1, 1, 1], [11, 22, 33], [1, 3, 4]]]) </code></pre> <p>... and n of course is, in general, a lot larger than 2, and the other axes are also larger than 3, so I don't want to loop over them if I don't need to.</p> <hr> <p>Update: The <code>[1,2,3]</code> (or whatever else I'm looking for) is not always at index 1. An example:</p> <pre><code>a = numpy.array([[[1,1,1],[1,2,3],[1,3,4]], [[1,2,3],[1,1,1],[1,3,4]]]) </code></pre>

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