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    <p><strong>EDIT</strong> Created functions that return the full set of numbers, not just one row at a time. <strong>EDIT 2</strong> Make the functions more pythonic (and faster), add solution for second question</p> <p>For the first set of numbers, you might consider <code>numpy.random.randint</code> or <code>numpy.random.uniform</code>, which take <code>low</code> and <code>high</code> parameters. Generating an array of 7 x 1,000,000 numbers in a specified range seems to take &lt; 0.7 second on my 2 GHz machine:</p> <pre><code>def LimitedRandInts(XLim, N): rowlen = (1,N) return [np.random.randint(low=0,high=lim,size=rowlen) for lim in XLim] def LimitedRandDoubles(XLim, N): rowlen = (1,N) return [np.random.uniform(low=0,high=lim,size=rowlen) for lim in XLim] &gt;&gt;&gt; import numpy as np &gt;&gt;&gt; N = 1000000 #number of randoms in each range &gt;&gt;&gt; xLim = [x*500 for x in range(1,8)] #convenient limit generation &gt;&gt;&gt; fLim = [x/7.0 for x in range(1,8)] &gt;&gt;&gt; aa = LimitedRandInts(xLim, N) &gt;&gt;&gt; ff = LimitedRandDoubles(fLim, N) </code></pre> <p>This returns integers in [0,xLim-1] or floats in [0,fLim). The integer version took ~0.3 seconds, the double ~0.66, on my 2 GHz single-core machine.</p> <p>For the second set, I used @Joe Kingston's suggestion.</p> <pre><code>def SumToOneRands(NumToSum, N): aa = np.random.uniform(low=0,high=1.0,size=(NumToSum,N)) #13 rows by 1000000 columns, for instance s = np.reciprocal(aa.sum(0)) aa *= s return aa.T #get back to column major order, so aa[k] is the kth set of 13 numbers &gt;&gt;&gt; ll = SumToOneRands(13, N) </code></pre> <p>This takes ~1.6 seconds.</p> <p>In all cases, <code>result[k]</code> gives you the kth set of data.</p>
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    1. POFastest Way to generate 1,000,000+ random numbers in python
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    1. COyou may win few cycles if you multiply by inverse instead of dividing in floating-point performance.
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    2. COI'll have to give that a whack. Do you know the performance of stacking arrays horizontally (not sure how to word this) to combine the arrays?
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    3. CO@aaa - Thanks, I pulled your suggestion into the answer. @Sandro - I think stack is not great. You might be able to preallocate the array. I'll see if I can make that work and update the answer.
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