Reshaping an array to 2-D by specifying only the column size

Question

I have a vector of length, lets say 10:

foo = np.arange(2,12)

In order to convert it to a 2-D array, with lets say 2 columns, I use the command reshape with following arguments:

foo.reshape(len(foo)/2, 2)

I was wondering if there is a more elegant way/syntax to do that (may be sth like foo.reshape(,2) )

Answer 1

You almost had it! You can use -1.

>>> foo.reshape(-1, 2)
array([[ 2,  3],
       [ 4,  5],
       [ 6,  7],
       [ 8,  9],
       [10, 11]])

As the reshape docs say:

newshape : int or tuple of ints
    The new shape should be compatible with the original shape. If
    an integer, then the result will be a 1-D array of that length.
    One shape dimension can be -1. In this case, the value is inferred
    from the length of the array and remaining dimensions.