Distance measurement - Hamming distance

Python Learning Series ： Catalog

One 、 summary

Hamming distance （Hamming Distance）, Is the number of replacements required to change one string into another .

Two 、 Calculation method

for instance ,

1. 1011101 And 1001001 Of Hamming distance by 2

type 1	1	0	1	1	1	0	1
type 2	1	0	0	1	0	0	1

As long as type 1 Just change the red part .

2. 2143896 And 2233786 Of Hamming distance by 3

type 1	2	1	4	3	8	9	6
type 2	2	2	3	3	7	9	6

As long as type 1 Just change the red part .

3. helloworld And hollowoold

type 1	h	e	l	l	o	w	o	r	l	d
type 2	h	o	l	l	o	w	o	o	l	d

As long as type 1 Just change the red letter of the bid .

3、 ... and 、 Hamming weight

Hamming weight Is the Hamming distance of a string relative to a zero string of the same length ; in other words , It's the number of non-zero elements in a string ： For binary strings , Namely 1 The number of , therefore 11101 The weight of Han Ming is 4.

therefore , If the elements in vector space a and b The Hamming distance between them is equal to the difference of their Hamming weight a-b.