Numpy: ValueError:包含多个元素的数组的真值是不明确的。使用a.any()或所有()

I've been trying to use numpy on Python to plot some data. However I'm getting an error I don't understand:

我一直尝试在Python中使用numpy来绘制一些数据。但是我有一个错误，我不明白:

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

ValueError:具有多个元素的数组的真值是不明确的。使用a.any()或所有()

And this is the line supposed to cause the error (the third line):

这条线应该引起误差(第三行):

def T(z):
for i in range(3):
    if (z <= z_tbl[i+1]):
        return T0_tbl[i]+a_tbl[i]*(z-z_tbl[i])
return 0

Those lists are just some lists of integers, and z is an integer too

这些列表只是一些整数的列表，z也是一个整数。

How can i fix it?

我怎样才能修好它?

1 个解决方案

#1

Either z or z_tbl[i+1] is a numpy array. For numpy arrays, rich comparisons (==, <=, >=, ...) return another (boolean) numpy array.

z或z_tbl[i+1]是一个numpy数组。对于numpy数组，rich比较(==，<=，>=，…)返回另一个(boolean) numpy数组。

bool on a numpy array will give you the exception that you are seeing:

在numpy数组中bool将会给您一个您正在看到的异常:

>>> a = np.arange(10)
>>> a == 1
array([False,  True, False, False, False, False, False, False, False, False], dtype=bool)
>>> bool(a == 1)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all()

Numpy is trying to tell you what to do:

Numpy试图告诉你该做什么:

>>> (a == 1).any()  # at least one element is true?
True
>>> (a == 1).all()  # all of the elements are true?
False

#1