I suggest shuffling a copy of the array using the Fisher-Yates shuffle and taking a slice: function getRandomSubarray(arr, size) { var shuffled = arr.slice(0), i = arr.length, temp, index; while (i–) { index = Math.floor((i + 1) * Math.random()); temp = shuffled[index]; shuffled[index] = shuffled[i]; shuffled[i] = temp; } return shuffled.slice(0, size); } var x … Read more
ISNUMERIC will not do – it tells you that the string can be converted to any of the numeric types, which is almost always a pointless piece of information to know. For example, all of the following are numeric, according to ISNUMERIC: £, $, 0d0 If you want to check for digits and only digits, … Read more
pi isn’t exactly representable as Python float (same as the platform C’s double type). The closest representable approximation is used. Here’s the exact approximation in use on my box (probably the same as on your box): >>> import math >>> (math.pi / 2).as_integer_ratio() (884279719003555, 562949953421312) To find the tangent of that ratio, I’m going to … Read more
From this post: How to deal with floating point number precision in JavaScript? You have a few options: Use a special datatype for decimals, like decimal.js Format your result to some fixed number of significant digits, like this: (Math.floor(y/x) * x).toFixed(2) Convert all your numbers to integers
To answer your first question, numpy.correlate(a, v, mode) is performing the convolution of a with the reverse of v and giving the results clipped by the specified mode. The definition of convolution, C(t)=∑ -∞ < i < ∞ aivt+i where -∞ < t < ∞, allows for results from -∞ to ∞, but you obviously … Read more