array initialize
array_one_dimension = [ 0 for i in range(cols)]
array_multi_dimension = [[0 for i in range(cols)] for j in range(rows)]
numpy
- numpy.array()
- numpy.zeros()
- numpy.empty()
返回np.ndarray数组
np.ndarray属性
ndarray.shape #array的shape
ndarray.ndim #array的维度
ndarray.size #the number of ndarray in array
ndarray.dtype #type of the number in array
ndarray.itemsize #size of the element in array
array[array > 0].size #统计一个数组有多少个非零元素，不论array的维度是多少
numpy.array()
np.array(object,dtype=None,copy=True,order=False,subok=False,ndim=0)
numpy.zeros()
np.zeros(shape,dtype=float,order=‘C’)
numpy.empty()
np.empty(shape,dtype=float,order=‘C’)
numpy.random.randn(shape)
np.random.randn(3,4)