python - Numpy reshape 1d to 2d array with 1 column

Question

In numpy the dimensions of the resulting array vary at run time. There is often confusion between a 1d array and a 2d array with 1 column. In one case I can iterate over the columns, in the other case I cannot.

How do you solve elegantly that problem? To avoid littering my code with if statements checking for the dimensionality, I use this function:

def reshape_to_vect(ar):
    if len(ar.shape) == 1:
      return ar.reshape(ar.shape[0],1)
    return ar

However, this feels inelegant and costly. Is there a better solution?

Answer 1

The simplest way:

ar.reshape(-1, 1)