ValueError错误：矩阵不是复制错误和X对准[：] [英] ValueError: matrices are not aligned for copy error and x[:]

问题描述

我得到了ValueError错误为如下。

I got the ValueError as given below.

ValueError错误：矩阵不是复制错误对齐

ValueError: matrices are not aligned for copy error

据被曝以下行（我没有写这个code，我想使用它）：

It was traced to the following line (I did not write this code, I am trying to use it):

x1[:] =  _dotproduct(x1, u)

点积就像numpy的点积，它工作正常，印刷_dotproduct（X1，U）给出一个有效的答案。这是 X1 [：] 不工作

The dot product is like numpy dot product, it works FINE, printing _dotproduct(x1, u) give a valid answer. It is x1[:] that is not working.

这是什么 [：] 是什么意思？我从来没有见过的。

What does [:] mean? I have never seen that.

此外，我怎么能解决定位的错误？

Also how can I solve the error of alignment?

编辑：结果
我现在已经追查错误 X1 [：] ，所以这不是我可以做到以下几点：

I have now traced the error to x1[:], so instead of this can I do the following:

hh=len(x1)

X1 [0：HH] = _数量积（X1，U）

推荐答案

在此情况下，由于它是在 = 标志的左侧，这是一个切片赋值。对象 X1 保持相同的对象，但是其所有内容都与右侧的序列所取代。如果没有 [：] ， X1 将被分配到一个完全不同的对象

In this case, since it's on the left side of the = sign, it's a slice assignment. The object x1 remains the same object, but all its contents are replaced with the sequence on the right. Without the [:], x1 would be assigned to a totally different object.

使用切片分配意味着如果在你的程序中相同的变量其它引用，这些都将看到新的内容。例如，函数的调用者传递一个容器和函数替换其内容。这不会没有切片分配是可能的。

Using a slice assignment means that if there are other references to the same variable in your program, all of these will see the new contents. For example, the caller of a function passes in a container and the function replaces its contents. This wouldn't be possible without the slice assignment.

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