总结了最常用,需要注意的一些numpy方法,做个记录
import numpy as np
from numpy import *
from matplotlib.pylab import plt
a = mat([[1, 2], [3, 4]]); print(a)
b = np.zeros((3, 4)); print(b)
c = np.ones((2, 4)); print(c)
d = np.eye(5); print(d)
e = np.random.rand(2, 2); print(e)
f = np.random.randint(2, 8, size=[2, 5]); print(f)
g = np.diag([1, 2, 3]); print(g)
h = np.arange(2, 13, 3); print(h)
A = np.array([[1, 2, 9], [7, 5, 6]])
B = np.array([[2, 3, 4], [4, 8, 6], [7, 8, 9]])
C = np.array([[2, 3, 4], [4, 5, 6]])
print(A.shape, B.shape)
print(A * C)
print(A.dot(B)); print(np.dot(A, B))
print(np.linalg.inv(B))
print(A.T)
print(A.sum(axis=0)); sum(A,1); sum(A[2:5], 0)
print(A.max(axis=0)); A.max(1); max(A[2:5],0)
print(A.min(0)); A.min(1); min(A[2:5],1)
print(A.argmax(axis=0)); argmax(A[2:5],1)
print(A.argmin(0)); print(argmin(A[0:2],0))
A = [
[1, 2, 3, 4, 6],
[2, 2, 3, 4, 6],
[3, 2, 3, 4, 6],
[4, 2, 3, 4, 6],
[5, 2, 3, 4, 6]
]
print(A[1:5] )
print(A[2:] )
print(A[:5] )
print(A[::2] )
print(A[1:5:2] )
print(A[-1:-4:-1] )
print(A[-1::-1] )
print(A[-2:-5:-2] )
print(A[1:-2] )
print(A[-1:2:-1] )
A = [[1, 2, 3], [4, 5, 6]]
B = [[2, 3, 4], [5, 5, 5]]
print(np.vstack((A, B)))
print(np.hstack((A, B)))
a = np.array([1, 2, 3]); b = np.array([4, 5, 6])
print(np.c_[a,b])
print(np.r_[a,b])
a = np.array([[0],[1],[2],[3]]);
b = np.array([1, 2, 3]);
print(a + b)
a = np.ones([3, 3, 1])
b = np.array([1, 1, 1])
print(a + b)
print(np.tile([4, 3],(3,2)));
x=[1.5,0.8,2.6,1.0,0.6,2.8,1.2,0.9,0.4,1.3,1.2,2.0,1.6,1.8,2.2]
y=[3.1,1.9,4.2,2.3,1.6,4.9,2.8,2.1,1.4,2.4,2.4,3.8,3.0,3.4,4.0]
plt.plot(x, y, 'r.')
plt.show()
plt.scatter(x, y, c='r', marker='x')
plt.show()
numpy.random
import numpy as np
a = np.random.random((1000, 20))
print(a, a.shape)
b = np.random.rand(1000, 20)
print(b, b.shape)
c = np.random.randn(10, 2)
print(c, c.shape)
d = np.random.standard_normal(10)
print(d)
e = np.random.random_integers(2, 100, (100, 2))
print(e)
f = np.random.random_sample((100, 2))
print(f, f.shape)
g = np.random.choice([1, 2, 5], size=None, replace=True, p=None)
print(g)
h = [1, 2, 3]
np.random.shuffle(h)
print(h)
i = [1, 2, 3]
j = np.random.permutation(i)
print(i, j)