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Jul 12, 2011 · Coming from other languages: it IS a difference between an 1D-Array containing 1D-Arrays and a 2D-Array. And AFAIK there is no way of having a multi-dimensional-array (or list) in python. Should be said here...
@codemuncher The reason that [[0] * col] * row doesn't do what you want is because when you initialize a 2d list that way, Python will not create distinct copies of each row. Instead it will init the outer list with pointers to the same copy of [0]*col .
Nov 11, 2020 · Applying np.array will give you a 2 element numpy array where each element is a list object as - array([list([1, 2]), list([3, 4, 5])], dtype=object). I believe this is the issue you are facing. You cant create a 2D matrix for example that looks like -
To create an empty multidimensional array in NumPy (e.g. a 2D array m*n to store your matrix), in case you don't know m how many rows you will append and don't care about the computational cost Stephen Simmons mentioned (namely re-buildinging the array at each append), you can squeeze to 0 the dimension to which you want to append to: X = np.empty(shape=[0, n]).
Sep 25, 2012 · I want to convert a 1-dimensional array into a 2-dimensional array by specifying the number of columns in the 2D array. Something that would work like this: > import numpy as np > A = np.arr...
Jun 8, 2014 · (P.S. It's a good idea to get in the habit of saying list when you mean list and reserving array for numpy ndarrays. There's actually a built-in array module with its own array type, so that confuses things even more, but it's relatively seldom used.)
May 14, 2013 · How can I create a partitioned table with the addition of a unique index in SQL Server? What's a good way to introduce the player-characters in the first session of a campaign? When choosing between competing metaphysical theories to determine which best explains the data, how can we first decide what qualifies as "the data"?
Mar 16, 2018 · Is there a built-in function to join two 1D arrays into a 2D array? Consider an example: X=np.array([1,2]) y=np.array([3,4]) result=np.array([[1,3],[2,4]]) I can think of 2 simple solutions. The first one is pretty straightforward. np.transpose([X,y]) The other one employs a lambda function. np.array(list(map(lambda i: [a[i],b[i]], range(len(X)))))
Mar 19, 2019 · The problem is on the initialization step. for i in range (0,m): matrix[i] = columns This code actually makes every row of your matrix refer to the same columns object.
There is no array type in python, but to emulate it we can use lists. I want to have 2d array-like structure filled in with zeros. My question is: what is the difference, if any, in this two expressions: zeros = [[0 for i in xrange(M)] for j in xrange(M)] and. zeros = [[0]*M]*N
