Oct 3, 2009 · @AndersonGreen As I said there's no such thing as a variable declaration in Python. You would create a multidimensional list by taking an empty list and putting other lists inside it or, if the dimensions of the list are known at write-time, you could just write it as a literal like this: my_2x2_list = [[a, b], [c, d]].

Python's array module. The standard library also has the array module, which is a wrapper over C arrays. Like C arrays, array.array objects hold only a single type (which has to be specified at object creation time by using a type code), whereas Python list objects can hold anything.

Dec 7, 2009 · The second parameter to array.array is a generator, which constructs the defined sequence as it is read. This way, the array module can consume the zeros one-by-one, but the generator only uses constant memory. This generator does not get bigger (memory-wise) if the sequence gets longer. The array will grow of course, but that should be obvious.

One thing to note: all elements in the list will have initially the same id (or memory address). When you change any element later on in the code, this will impact only the specified value, - HOWEVER - if you create a list of custom objects in this way (using the int multiplier) and later on you change any property of the custom object, this will change ALL the objects in the list.

Aug 16, 2013 · In python you can do this very eaisly start=0 end=10 arr=list(range(start,end+1)) output: arr=[0,1,2,3,4,5,6,7,8,9,10] or you can create a recursive function that returns an array upto a given number:

Jul 12, 2011 · In Python 3 there is no xrange but if you must use Python 2 then xrange is the correct function to use if you don't want to needlessly create objects. – Jade Commented Nov 25, 2015 at 7:29

Oct 11, 2019 · $ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a.fill(np.nan)" 10000 loops, best of 3: 54.3 usec per loop $ python -mtimeit "import numpy as np; a = np.empty((100,100));" "a[:] = np.nan" 10000 loops, best of 3: 88.8 usec per loop The timings show a preference for ndarray.fill(..) as the faster alternative. OTOH, I like numpy ...

this syntax for building an array of bytes works the same as for a string type: you can use + or other similar operators to build your byte array dynamically. – Adrien Plisson Commented Sep 26, 2011 at 14:49

May 20, 2012 · I would like to create a 3D array in Python (2.7) to use like this: distance[i][j][k] And the sizes of the array should be the size of a variable I have.

Another option would be to store your arrays as one contiguous array and also store their sizes or offsets. This takes a little more conceptual thought around how to operate on your arrays, but a surprisingly large number of operations can be made to work as if you had a two dimensional array with different si