Python Learning Note 1-numpy/enumerate

1. Np.size and Np.prod

1 Import NumPy as NP 2 x = Np.zeros ((3, 5,  2), dtype=np.complex128)3# Ndarray.size is the number of elements in the array4#  equivalent to Np.prod (a.shape)5Print  (x.size)6print(Np.prod (X.shape))

2. The enumerate () function is a python built-in function, enumerated on a dictionary, enumerated, and, for an iterative (iterable)/Ergodic object, enumerate an index sequence that can be used to obtain both the index and the value. Note: Enumerate is used in the for loop to get counted.

Examples of Use:

(1) For lists, you must traverse the index and iterate over the elements

1List1 = ["it","is a","a","Test"]2 #Method 13  forIinchRange (len (list1)):4     Print(i, list1[i])5 #Method 2 Use Enumerate6  forIndex, iteminchEnumerate (list1):7     Print(Index, item)

(2) Enumerate can also receive the second parameter, which is used to specify the starting value of an index

1List1 = ["it","is a","a","Test"]2  forIndex, iteminchEnumerate (List1, 1):3     Print(Index, item)4 " "5 1 This6 2 is7 31 x8 4 Testing9 " "

(3) Enumerate used to count file lines

1 # Method 1 2 ' R ' ). ReadLines ())3#  Method 24 count =-15 for inch ' R ' )):6     count + = 1

Python Learning Note 1-numpy/enumerate