The python source code is explained as follows:
map(func, *iterables) --> map object
Make an iterator that computes the function using arguments from
each of the iterables. Stops when the shortest iterable is exhausted.
To put it simply,
map() receives a function f and an iterable object (understood as a list here), and by applying the function f to each element of the list in turn, it gets a new list and returns it.
For example, for list [1, 2, 3, 4, 5, 6, 7, 8, 9]
If you want to square each element of the list, you can use the map() function:
Therefore, we only need to pass in the function f(x)=x*x, and then we can use the map() function to complete this calculation:
def f(x):
return x*x
print(list(map(f, [1, 2, 3, 4, 5, 6, 7, 8, 9])))
output result:
[1, 4, 9, 10, 25, 36, 49, 64, 81]
Use with anonymous functions:
data = list(range(10))
print(list(map(lambda x: x * x, data)))
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]
Note: The map() function does not change the original list, but returns a new list.
Using the map() function, one list can be converted to another list, and only the conversion function needs to be passed in.
Since the elements contained in a list can be of any type, map() can not only process lists that contain only numeric values, but in fact it can process lists that contain any type, as long as the passed function f can handle this data type.
The task
assumes that the English name entered by the user is not standardized, and does not follow the rules of first letter capitalization and subsequent letters lowercase. Please use the map() function to turn a list (containing a number of irregular English names) into a list containing standardized English names :
def f(s):
return s[0:1].upper() + s[1:].lower()
list_ = ['lll', 'lKK', 'wXy']
a = map(f, list_)
print(a)
print(list(a))
Copy code
Run result:
<map object at 0x000001AD0A334908>
[‘Lll’, ‘Lkk’, ‘Wxy’]