Numpy数组的保存与读取方法

np.save("filename.npy",a)
b = np.load("filename.npy")

np.savetxt("filename.txt",a)
b = numpy.loadtxt("filename.txt", delimiter=',')

a.tofile("filename.bin")
b = np.fromfile("filename.bin",dtype = **)

> a = np.arange(0,12)
> a.shape = 3,4
> a
array([[ 0, 1, 2, 3],
    [ 4, 5, 6, 7],
    [ 8, 9, 10, 11]])
> a.tofile("a.bin")
> b = np.fromfile("a.bin", dtype=np.float) # 按照float类型读入数据
> b # 读入的数据是错误的
array([ 2.12199579e-314,  6.36598737e-314,  1.06099790e-313,
     1.48539705e-313,  1.90979621e-313,  2.33419537e-313])
> a.dtype # 查看a的dtype
dtype('int32')
> b = np.fromfile("a.bin", dtype=np.int32) # 按照int32类型读入数据
> b # 数据是一维的
array([ 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11])
> b.shape = 3, 4 # 按照a的shape修改b的shape
> b
array([[ 0, 1, 2, 3],
    [ 4, 5, 6, 7],
    [ 8, 9, 10, 11]])