On 26/02/2014 00:04, JB wrote: > At the risk of igniting a flame war...can someone please help me understand > the indexing behavior of NumPy? I will readily I admit I come from a Matlab > background, but I appreciate the power of Python and am trying to learn more. > >>From a Matlab user's perspective, the behavior of indexing in NumPy seems > very bizarre. For example, if I define an array: > > x = np.array([1,2,3,4,5,6,7,8,9,10]) > > If I want the first 5 elements, what do I do? Well, I say to myself, Python > is zero-based, whereas Matlab is one-based, so if I want the values 1 - 5, > then I want to index 0 - 4. So I type: x[0:4]
The Python slicing syntax a:b defines the interval [a, b), while the Matlab syntax defines the interval [a:b]. This post from Guido van Rossum (the creator of Python) explains the choice of zero indexing and of this particular slice notation: https://plus.google.com/115212051037621986145/posts/YTUxbXYZyfi I actually find how Python works more straight forward: obtaining the first n elements of array x is simply x[:n], and obtaining n elements starting at index i is x[i:i+n]. Cheers, Daniele _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
