[Numpy-discussion] ndarray.T2 for 2D transpose

Juan Nunez-Iglesias jni.soma at gmail.com
Tue Apr 5 22:49:45 EDT 2016


Would you consider a 1D array to be a row vector or a column vector for the
purposes of transposition? The "correct" answer is not clear to me.


On Wed, Apr 6, 2016 at 12:26 PM, Alan Isaac <alan.isaac at gmail.com> wrote:

> On 4/5/2016 10:11 PM, Todd wrote:
>> When you try to transpose a 1D array, it does nothing.  This is the
>> correct behavior, since it transposing a 1D array is meaningless.
>> However, this can often lead to unexpected errors since this is rarely
>> what you want.  You can convert the array to 2D, using `np.atleast_2d`
>> or `arr[None]`, but this makes simple linear algebra computations more
>> difficult.
>> I propose adding an argument to transpose, perhaps called `expand` or
>> `expanddim`, which if `True` (it is `False` by default) will force the
>> array to be at least 2D.  A shortcut property, `ndarray.T2`, would be
>> the same as `ndarray.transpose(True)`.
> Use `dot`.  E.g.,
>         m.dot(a)
> hth,
> Alan Isaac
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