How to get a specific data from a json file using python and index number

Question

I want to get an url from a json file like this one:

[
    {
        "Index": 6,
        "Title": "A Simple Monitoring",
        "URL": "http://www.vn-meido.com/k1/index.php?PHPSESSID=4e30s552gamla57pl6hdhe2cn4&topic=1497.msg20688"
    },
    {
        "Index": 7,
        "Title": "A Simple Survey",
        "URL": "http://www.vn-meido.com/k1/index.php?PHPSESSID=4e30s552gamla57pl6hdhe2cn4&topic=1283.0"
    },
]

is there any method using the "Index" number to get the url?

Answer 1

Ah, so it's a list of dictionaries, seems like you could use a list comprehension to effectively "filter" the list.

eg you want the urls for index 6, 7, & 11

wanted_url_ids = [6, 7, 11]
[url_dict for url_dict in json_file if url_dict[index] in wanted_url_ids]

Answer 2

You can achieve this by creating a dictionary in python, which requires looping over the list when indexing.

dat = [
    {
        "Index": 6,
        "Title": "A Simple Monitoring",
        "URL": "http://www.vn-meido.com/k1/index.php?PHPSESSID=4e30s552gamla57pl6hdhe2cn4&topic=1497.msg20688"
    },
    {
        "Index": 7,
        "Title": "A Simple Survey",
        "URL": "http://www.vn-meido.com/k1/index.php?PHPSESSID=4e30s552gamla57pl6hdhe2cn4&topic=1283.0"
    },
]

dat_dict = {}

for item in dat:
    dat_dict[item['Index']] = item['URL']

print(dat_dict[6])
print(dat_dict[7])

After the dictionary was created, accessing elements from it would be much faster than looping through on the entire list every time.