numpy的一些用法

import numpy as np
array=np.array([[1,2,3],
               [2,3,4]],dtype=np.int)

print(array.dtype)
print("number of dim",array.ndim)
print("shape",array.shape)
print("size",array.size)
z=np.zeros((3,4))
b=np.ones((2,3))
print(z,b)
c=np.linspace(1,10,6).reshape((2,3))
print(c)
a=np.array([[1,1],
            [0,1]])
b=np.arange(4).reshape(2,2)
c=10*np.sin(a)
print(a*b)
print(a.dot(b))
a=np.random.random((2,4))
print(a)
print(np.sum(a))
print(np.min(a))
print(np.max(a))
a=np.arange(3,15).reshape((3,4))
print(a)
print(a[2][1])
print(a[2,:])
print(a[1,1:2])
for columm in a.T:
    print( columm)
print(a.flatten())
for item in a.flat:
    print(item)
    
    
a=np.array([1,1,1])[:,np.newaxis]
b=np.array([2,2,2])[:,np.newaxis]
print(np.vstack((a,b)))#vertical stack
print(np.hstack((a,b)))
print(a.T.shape)
print(a[:,np.newaxis])
c=np.concatenate((a, b,b,a),axis=0)
print(c)
a=np.arange(12).reshape(3,4)
print(a)
print(np.split(a,2,axis=1))
print(np.split(a,2,axis=1))
print(np.array_split(a,3,axis=1))
print(np.vsplit(a,3))

b=a
c=a
d=b
a[2][1]=100
print(a)
print(b is a)
b=a.copy()
a[2][1]=1500
print(a)
print(b)