重塑和融合4D至3D阵列

Question

l'm working with 4D arrays in numpy. l would like to append the data in forth dimension as follow :

1) inputs :

data_1_1=dim(2,4,130,10)
data_1_2=dim(2,4,130,10)

expected output :

data_1=dim(2,4,130,20)

2) reduce 4D array to 3D array inputs :

data_2_1=dim(3,5,130,20)

expected output :

data_2_1=dim(15,130,20)

Sorry for my newbie question.

Thank you for your help

What l have tried ? 1)

data_1= np.concatenate((data_1_1[...,np.newaxis],data_1_2[...,np.newaxis]),axis=2)

l'm wondering if this solution do the right job. since l would like to concatenate on the last dimension. In which order it's done ? Is is correct ?

2) For this case l don't have any idea

Answer 1

For the first part you need to say you want a specific axis to work on:

>>>x=np.arange(2*4*130*10).reshape(2,4,130,10)
>>>np.concatenate((x,x),axis=3).shape
(2, 4, 130, 20)

and for the second part, sounds like you want a reshape

>>>y=np.arange(3*5*130*20).reshape(3,5,130,20)
>>> y.reshape(15,130,20).shape
(15, 130, 20)

The numpy terms you need to acquaint yourself with are axis and shape - a good read on these will help you a lot.