[Python] Three methods to compare the list of one-dimensional array and the list of two-dimensional array and extract only the matching values [json]

Overview

As the title says. ** How to get the value in the [name] column of B when the value in the list (A) of the one-dimensional array exists in the [ID] column of the list (B) of the two-dimensional array. ** ** The above is what I learned while playing with the slack api, and I've summarized it below.

A.list

print(name_list)
['U012JDYRD2T', 'U012X478FNZ']

B.list　#It has been modified to make it easier to see.

print(data)
[['name',     'id'],
 ['Slackbot', 'USLACKBOT'],
 ['test_1',   'U012JDYRD2T'], #I want here
 ['test_5',   'U012JDYSN07'],
 ['kita',     'U012X478FNZ'],#I want here
 ['test_4',   'U012XQBE63X'],
 ['test_bot', 'U012YTNNPB5'],
 ['test_3',   'U012ZC8AQ8K'],
 ['tese_2',   'U013BQDLK6V']]

Expected results.py

print(result)
['test_1','kita']

Method 1

1.py

result = []
for data_id in data:
    if data_id[1] in name_list:
        result.append(data_id[0])

(1) For loops [data_id in data], data is stored in data_id one by one. ② [if data_id [1] in name_list] is a condition that the [id] column (data_id [1]) and name_list match. ③ [result.append (data_id [0])] adds the [name] column (data_id [0]) to the list called [result]

Method 2

1.py

result = []
result = [data_id[0] for data_id in data if data_id[1] in name_list]

The theory is the same as method 1. smart.

Method 3

3.py

r = []
r2 = []
for i in data:
    r = r + i
for i in name_list:
    tmp = (r.index(i)) - 1
    r2.append(r[tmp])

① Store data one by one in r. It is stored as ['name','id','Slackbot','USLACKBOT'…]. (2) Use the fact that name and id are stored in order. In other words, the one before " U012X478FNZ " is " kita ", and the one before " U012JDYRD2T " is " test_1 ". ③ So, in [tmp = (r.index (i)) -1], you can get the index of" kita "immediately before that by [-1] from the index (number) of" U012X478FNZ ". it can. ④ And the value of the acquired index is added to [r2].

What I found

You need to understand more about loops and conditionals.