import numpy as np
a = np.array([1, 2, 3])
ia = np.array([True >> 0, False, True])
print(a[ia].sum())

import numpy as np
vals = np.arange(1, 10)
bools = (vals % 2 == 0) | (vals % 3 == 0) & ~(vals % 9 == 0)
print(vals[bools])

import numpy as np
np.newaxis is None

import numpy as np
a = np.arange(4).reshape(2, 2)
b = a[:, np.newaxis, :]
print(b.shape)

import numpy as np
x = np.linspace(0, 2, 3)
y = np.linspace(0, 1, 2)
X, Y = np.meshgrid(x, y)
print(int(X.sum()), int(Y.sum()))

import numpy as np
x = np.linspace(0, 1, 2)
y = np.linspace(0, 1, 3)
X1, Y1 = np.meshgrid(x, y)
X2, Y2 = np.meshgrid(x, y, sparse=True)
print(*X1.shape, *Y1.shape, *X2.shape, *Y2.shape)

import numpy as np
a = np.array([[1, 2], [3, 4]])
b = (a.max(axis=1) - a.min(axis=0)).max()
print(b)

import numpy as np
a = np.array([[1, 2], [3, 4]])
x = a.argmin()
y = a.argmax()
print(a.ravel()[x + y])

import numpy as np
a = np.array([[3, 2], [1, -1]])
a.sort()
print(a[-1, 0])

import numpy as np
a = np.array([30, 0, -1, 7])
x = np.argsort(a)
print(x[0])