In Python, the reduce() function is declared in the functools. And it has the following function signature:
1 | reduce(method, data, initial_value); |
reduce(method, data, initial_value);
The reduce() function will iterate over the data array (or list), and accumulate a value (set to initial_value first) using the given function which has the following signature:
1 2 | def reducer_method(accumulated_value, current_value): pass |
def reducer_method(accumulated_value, current_value): pass
For example, to sum up all the values from 1 to 100, you can use this:
1 2 | from functools import reduce reduce(lambda s, cur: s + cur, range(101), 0) |
from functools import reduce reduce(lambda s, cur: s + cur, range(101), 0)
As we can see, the reducer function for sum is passed as a lambda function, which is essentially the same as:
1 2 | def reducer_sum(s, cur): return s + cur |
def reducer_sum(s, cur): return s + cur
The reduce() function in Python allows you to do one-liner without need to write a loop.
How is reduce() implemented in Python?
The reduce() function is as simple as the following:
1 2 3 4 5 | def reduce(reducer, data, value): cur = value for i in data: cur = reducer(cur, i) return cur |
def reduce(reducer, data, value):
cur = value
for i in data:
cur = reducer(cur, i)
return cur–EOF (The Ultimate Computing & Technology Blog) —
GD Star Rating
loading...
248 wordsloading...
Last Post: The Combination Function and Iterator using Depth First Search Algorithm
Next Post: How to Solve SMTP: Could Not Authenticate using Gmail + PHPMailer?
