逐行插入2D Numpy数组的值 [英] Interpolate values row-wise for 2D Numpy array

问题描述

我有两个numpy数组:

I have two numpy arrays:

x = np.array([1,2,3,4,5])
y = np.array([10,20,30,40,50])

我试图得到的是这样的:

What I try to get is something like this:

array([[  1.  ,   3.25,   5.5 ,   7.75,  10.  ],
       [  2.  ,   6.5 ,  11.  ,  15.5 ,  20.  ],
       [  3.  ,   9.75,  16.5 ,  23.25,  30.  ],
       [  4.  ,  13.  ,  22.  ,  31.  ,  40.  ],
       [  5.  ,  16.25,  27.5 ,  38.75,  50.  ]])

我的方法不是很像Numpy，需要对非常大的数组进行改进(摆脱for循环):

My approach is not very Numpy like and needs improvement (getting rid of the for-loop) for very large arrays:

myarray = np.zeros((5,5))
for idx in np.arange(5):
    myarray[idx,:] = np.linspace(x[idx], y[idx], 5)

在Numpy中执行此操作的最佳方法是什么? 这样生成myarray然后对其进行操作会更好吗?

What would be a good approach to do this in Numpy? Would it be better to generate the myarray this way and then manipulate it?

myarray = np.zeros((5,5))
myarray[:,0] = x
myarray[:,-1] = y

array([[  1.,   0.,   0.,   0.,  10.],
       [  2.,   0.,   0.,   0.,  20.],
       [  3.,   0.,   0.,   0.,  30.],
       [  4.,   0.,   0.,   0.,  40.],
       [  5.,   0.,   0.,   0.,  50.]])

推荐答案

此广播技巧有效:

>>> x = np.array([1,2,3,4,5])
>>> y = np.array([10,20,30,40,50])
>>> z = np.linspace(0, 1, 5)
>>> z[None, ...] * (y[..., None] - x[..., None]) + ( x[..., None])
array([[  1.  ,   3.25,   5.5 ,   7.75,  10.  ],
       [  2.  ,   6.5 ,  11.  ,  15.5 ,  20.  ],
       [  3.  ,   9.75,  16.5 ,  23.25,  30.  ],
       [  4.  ,  13.  ,  22.  ,  31.  ,  40.  ],
       [  5.  ,  16.25,  27.5 ,  38.75,  50.  ]])
>>> 

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