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# Python | Multiply each item in the sublist by its index

Here are some ways to solve the problem.

Method # 1: Using the naive method

 ` # Python3 demo code ` ` # multiply the numbers with position ` ` # and add them to return num `   ` import ` ` numpy as np `   ` # initializing list ` ` ini_list ` ` = ` ` [[` ` 3 ` `, ` ` 4 ` `, ` ` 7 ` `], [` ` 6 ` `, ` ` 7 ` `, ` ` 8 ` `], [` ` 10 ` `, ` ` 7 ` `, ` ` 5 ` `], [` ` 11 ` ` , ` ` 12 ` `, ` ` 13 ` `]] ` ` `  ` # print initial_list ` ` print ` ` (` ` "initial_list" ` `, ini_list) ` ` `  ` res ` ` = ` ` [] ` ` # Using the naive method ` ` for ` ` sub_list ` ` in ` ` ini_list: ` ` sublistsum ` ` = ` ` 0 ` ` `  ` for ` ` i, value ` ` in ` ` enumerate ` ` (sub_list): ` ` sublistsum ` ` = ` ` sublistsum ` ` + ` ` i ` ` * ` ` value `   ` res.append (sublistsum) ` ` `  ` # print result `` print ( "result" , res) `

Output:

` initial_list [[3, 4, 7], [6, 7, 8], [10, 7, 5], [11, 12, 13]] result [18, 23, 17, 38 ] `

Method # 2: Using the comprehension list

 ` # Python3 demo code ` ` # multiply the numbers with position ` ` # and add them to return num `     ` # initializing list ` ` ini_list ` ` = ` ` [[` ` 3 ` `, ` ` 4 ` < code class = "plain">, ` 7 ` `], [` ` 6 ` `, ` ` 7 ` `, ` ` 8 ` `], [` ` 10 ` `, ` ` 7 ` `, ` ` 5 ` `], [` ` 11 ` `, ` ` 12 ` `, ` ` 13 ` `]] `   ` # print initial_list ` ` print ` ` (` ` "initial_list" ` `, ini_list) ` ` `  ` # Using comprehension list ` ` res ` ` = ` ` [` ` sum ` ` (i ` ` * ` ` j ` ` for ` ` i, j ` ` in ` ` enumerate ` ` (sublist)) ` ` ` ` for ` ` sublist ` ` in ` ` ini_list] `   ` # print result ` ` print ` ` (` ` "result" ` `, res) ` ` `

Exit:

` initial_list [ [3, 4, 7], [6, 7, 8], [10, 7, 5], [11, 12, 13]] result [18, 23, 17, 38] `

Method # 3: Using NumPy

 ` # Python3 demo code ` ` # multiply the numbers with position ` ` # and add them to return num `   ` import ` ` numpy as np `   ` # initializing list ` ` ini_list ` ` = ` ` [[[` ` 3 ` `, ` ` 4 ` `, ` ` 7 ` `], [` ` 6 ` `, ` ` 7 ` `, ` ` 8 ` `], [` ` 10 ` `, ` ` 7 ` `, ` ` 5 ` `], [` ` 11 ` `, ` ` 12 ` ` , ` ` 13 ` `]] `   ` # print initial_list ` ` print ` ` ( ` ` "initial_list" ` `, ini_list) `   ` # Using NumPy ` ` res ` ` = ` ` [np.arange (` ` len ` ` (sublist)). dot (sublist) ` ` for ` ` sublist ` ` in ` ` ini_list] ` ` `  ` # print result ` ` print ` ` (` `" result "` `, res) ` ` `  ` `

Exit:

` initial_list [[3, 4, 7], [6, 7, 8], [10, 7, 5], [11, 12 , 13]] result [18, 23, 17, 38] `

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