[Numpy-discussion] x[None] changes x.shape

Vincent Nijs v-nijs at kellogg.northwestern.edu
Fri Jan 5 18:54:35 CST 2007


Say I use a function that expects a boolean array called sel to be passed as
an argument:

def foo(x,sel = None):
    return x[sel]

If x is a 1-d array and sel is a (1-d) boolean array, x.shape will give (n,)
where n is len(x).

However, if the default value None is used (i.e., when no boolean array is
passed) x.shape will give (1,n).

Is that expected behavior?

If so is there an alternative default to I could use that would return the
entire x array and have x.shape be (n,)?

Vincent




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