>>> ar = np.arange(20)#一維數組>>>print(ar[4])#索引4>>>print(ar[4:7])#切片,左閉右開[456]>>> ar = np.arange(16).reshape(4,4)#二維數組>>>print(ar[:2,1:])#切片[[123][567]]>>>print(ar[2])#索引[891011]>>> ar = np.arange(8).reshape(2,2,2)#三維數組>>>print(ar[0])#索引[[01][23]]>>>print(ar[0][0])#索引[01]>>>print(ar[0][0][1])#索引1>>> ar = np.arange(10)>>> b = ar.copy()#複製,傳值>>> b[7:9]=200#附新值>>>print(ar)[0123456789]>>>print(b)[01234562002009]
3 隨機數
>>> sample = np.random.normal(size=(4,4))#正態分佈隨機數>>>print(sample)[[2.24138154e-011.30289275e+00-1.75193696e+00-3.72794238e-02][2.90698158e-01-1.22481090e+00-1.61384828e-03-8.41389311e-01][2.41947711e+002.42897439e-011.80080970e+00-8.58082546e-01][-8.78980085e-011.62853108e+00-1.78333195e+00-5.00738236e-02]]>>> b = np.random.rand(4)#4個[0,1)的隨機浮點數,均勻分佈>>>print(b,type(b))[0.783638670.222779170.244128910.84483113]<class'numpy.ndarray'>>>> c = np.random.rand(2,3)#2x3個[0,1)的隨機浮點數,均勻分佈>>>print(c,type(c))[[0.343394090.102865060.75058407][0.921306640.844124020.77756031]]<class'numpy.ndarray'>>>> b = np.random.randn(4)#4個[0,1)的隨機浮點數,正態分佈>>>print(b,type(b))[0.04014725-1.85238454-0.31065846-0.34918658]<class'numpy.ndarray'>>>> c = np.random.randn(2,3)#2x3個[0,1)的隨機浮點數,正態分佈>>>print(c,type(c))[[1.18949625-0.857080131.23795057][0.08689693.266362730.08522144]]<class'numpy.ndarray'>>>>print(np.random.randint(2,6,size=5))#隨機整數 (首元,末元,個數)[43325]>>>print(np.random.randint(2,6,(2,3)))#隨機整數 (首元,末元,維度)[[434][533]]