有效填充具有许多 if else 语句的多维数组

我想以特定且有效的方式填充 4dim numpy 数组。因为我不太了解，所以我开始用 if else 语句编写代码，但这看起来不太好，可能很慢，而且我也不能真正确定我是否考虑了每种组合。这是我停止写下的代码：

sercnew2 = numpy.zeros((gn, gn, gn, gn))
for x1 in range(gn):
    for x2 in range(gn):
        for x3 in range(gn):
            for x4 in range(gn):
                if x1 == x2 == x3 == x4: 
                    sercnew2[x1, x2, x3, x4] = ewp[x1]
                elif x1 == x2 == x3 != x4:
                    sercnew2[x1, x2, x3, x4] = ewp[x1] * ewp[x4]
                elif x1 == x2 == x4 != x3:
                    sercnew2[x1, x2, x3, x4] = ewp[x1] * ewp[x3]
                elif x1 == x3 == x4 != x2:
                    sercnew2[x1, x2, x3, x4] = ewp[x1] * ewp[x2]
                elif x2 == x3 == x4 != x1:
                    sercnew2[x1, x2, x3, x4] = ewp[x2] * ewp[x1]
                elif x1 == x2 != x3 == x4:
                    sercnew2[x1, x2, x3, x4] = ewp[x1] * ewp[x3]
                elif ... many more combinations which have to be considered

所以基本上应该发生的是，如果所有变量（x1、x2、x3、x4）彼此不同，则条目将是：

sercnew2[x1, x2, x3, x4] = ewp[x1]* ewp[x2] * ewp[x3] * ewp[x4]

现在，如果假设变量 x2 和 x4 相同，那么：

sercnew2[x1, x2, x3, x4] = ewp[x1]* ewp[x2] * ewp[x3]

其他例子可以在上面的代码中看到。基本上，如果两个或多个变量相同，那么我只考虑其中的一个。我希望模式是清晰的。否则请让我注意，我会尽力更好地表达我的问题。我很确定，有一种更智能的方法可以做到这一点。希望您能更好地了解并提前致谢:)

真的希望我能得到它！这是一种矢量化方法 -

from itertools import product

n_dims = 4 # Number of dims

# Create 2D array of all possible combinations of X's as rows
idx = np.sort(np.array(list(product(np.arange(gn), repeat=n_dims))),axis=1)

# Get all X's indexed values from ewp array
vals = ewp[idx]

# Set the duplicates along each row as 1s. With the np.prod coming up next,
#these 1s would not affect the result, which is the expected pattern here.
vals[:,1:][idx[:,1:] == idx[:,:-1]] = 1

# Perform product along each row and reshape into multi-dim array
out = vals.prod(1).reshape([gn]*n_dims)