Brief Introduction to the zip () and * zip () functions in Python and the python Functions

Brief Introduction to the zip () and * zip () functions in Python and the python Functions

Preface

1. experiment environment: Python 3.6;

2. Sample Code address: Download example;

3. The element in this article refers to the next-level project (which may be a single element or nested list) in the list, tuples, dictionaries, and other collection-type data types ).

Detailed description of the zip (* iterables) Function

Zip () function definition

Combine the elements of multiple iterators in the parameters into a new iterator;

Return Value:
Returns a zip object whose internal elements are tuples and can be converted to lists or tuples;

Input parameters: tuples, lists, dictionaries, and other iterators.

Zip () function usage

When the zip () function has only one parameter

Zip (iterable) extracts one tuples from the iterable to form one.

Example:

# Zip () function single parameter list1 = [1, 2, 3, 4] tuple1 = zip (list1) # print the zip function return type print ("zip () return type of the function: \ n ", type (tuple1) # convert a zip object to a list print (" convert a zip object to a list: \ n ", list (tuple1 ))

Output:

The return type of the zip () function:
<Class 'zip'>
Zip object to list:
[(1,), (2,), (3,), (4,)]

When the zip () function has two parameters, the zip (a, B) zip () function extracts one element from a and B to form a tuples, then combine the tuples in turn into a new iterator-the new zip type data.

Note: distinct requires that a and B have the same dimension. When the two have the same number of rows and number of columns, the corresponding position element can be normally combined;

Struct _ longest (* iterables) function.

Example:

m = [[1,2,3], [4,5,6], [7,8,9]] n = [[2,2,2], [3,3,3], [4,4,4]] p = [[2,2,2], [3,3,3,]

Zip (m, n) will return ([1, 2, 3], [2, 2, 2]), ([4, 5, 6], [3, 3, 3]), ([7, 8, 9], [4, 4, 4])

M [0], n [0]	M [1], n [1]	M [2], n [2]
[1, 2, 3] [2, 2]	[4, 5, 6] [3, 3]	[7, 8, 9] [4, 4]

Zip (m, p) will return ([1, 2, 3], [2, 2, 2]), ([4, 5, 6], [3, 3, 3])

M [0], n [0]	M [1], n [1]	M [2], n [2]
[1, 2, 3] [2, 2]	[4, 5, 6] [3, 3]	[7, 8, 9]

Sample Code:

# The zip () function has two parameters: m = [1, 2, 3], [4, 5, 6], [7, 8, 9] n = [[2, 2, 2], [3, 3, 3], [4, 4, 4] p = [2, 2, 2], [3, 3, 3] # print rows and columns ("rows and columns are the same: \ n", list (zip (m, n ))) # print different rows and columns ("different rows and columns: \ n", list (zip (m, p )))

Output:

The rows and columns are the same:
[([1, 2, 3], [2, 2, 2]), ([4, 5, 6], [3, 3, 3]), ([7, 8, 9], [4, 4, 4])]
Different rows and columns:
[([1, 2, 3], [2, 2, 2]), ([4, 5, 6], [3, 3, 3])]

Zip () function application

Matrix addition and subtraction, dot Multiplication

You can also use the for loop + list derivation;

m = [[1, 2, 3], [4, 5, 6], [7, 8, 9]] n = [[2, 2, 2], [3, 3, 3], [4, 4, 4]]

# Zip () Application # matrix addition and subtraction, point multiplication m = [[1, 2, 3], [4, 5, 6], [7, 8, 9] n = [[2, 2, 2], [3, 3, 3], [4, 4, 4] # print matrix point multiplication ('= *' * 10 + "Matrix point multiplication" + '= *' * 10) print ([x * y for, B in zip (m, n) for x, y in zip (a, B)]) # Add a matrix, subtract the same print ('= *' * 10 + "matrix, subtract "+ '= *' * 10) print ([x + y for a, B in zip (m, n) for x, y in zip (a, B)])

Output:

[2, 4, 6, 12, 15, 18, 28, 32, 36] [3, 4, 5, 7, 8, 9, 11, 12, 13]

* Detailed description of the zip (* iterables) Function

Zip (iterables) Function

* The zip () function is the inverse process of the zip () function. It turns the zip object into the data before the original combination.

Sample Code:

# * Zip () function print ('= *' * 10 + "* zip () function" + '= *' * 10) m = [[1, 2, 3], [4, 5, 6], [7, 8, 9] n = [[2, 2, 2], [3, 3, 3], [4, 4, 4] print ("* zip (m, n) returns: \ n", * zip (m, n) m2, n2 = zip (* zip (m, n) # True is returned if the values are equal. * print (m = list (m2) indicates the inverse process of zip) and n = list (n2 ))

Output:

* Zip (m, n) returns:
([1, 2, 3], [2, 2, 2]) ([4, 5, 6], [3, 3, 3]) ([7, 8, 9], [4, 4, 4])
True

Summary

Complete example: Download example

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