Python searching a Json with key value

Question

I'm having a JSON file and I'm trying to do a search using the values ( not the keys). Is there a built in function in Python that does so?

 [["2778074170846781111111110", "a33104eb1987bec2519fe051d1e7bd0b4c9e4875"],
  ["2778074170846781111111111", "f307fb3db3380bfd27901bc591eb025398b0db66"]]

I thought of this approach. Loading the file into a list and start searching. Is there a more efficient way?

def OptionLookUp(keyvalue):
    with open('data.json', 'r') as table:
        x= json.loads(table)

it is normal 2-dimensional list (not dictionary) so you don't have keys - only values. And what do you want to find ? Use for-loop to check every row. — furas
– furas, Commented Nov 21, 2016 at 15:11
As furas says, it is 2-dimensional list (python) or when talking about JSON it's 2-dimensional array. This is key-value JSON: { 'key': 'value' }. As furas asks, what is the example of "keyvalue" you are passing the the function? — Peter Majko
– Peter Majko, Commented Nov 21, 2016 at 15:12
Ture, but it is still a valid JSON. You can check it here jsonlint.com — Joseph Wahba
– Joseph Wahba, Commented Nov 21, 2016 at 15:13
Please specify (with input / output examples) what you mean by "searching" ? — bruno desthuilliers
– bruno desthuilliers, Commented Nov 21, 2016 at 15:14
input = a33104eb1987bec2519fe051d1e7bd0b4c9e4875 Output = 2778074170846781111111110 I already did it like this def OptionLookUp(key): with open('data.json', 'r') as table: x= json.load(table) for i in x: if (i[1] == key): print i — Joseph Wahba
– Joseph Wahba, Commented Nov 21, 2016 at 15:18

Peter Majko · Accepted Answer · 2016-11-21 15:25:19Z

1

After your edit I can say that there is no faster/more efficient way than turning your JSON into python 2-dimensional list and loop through each node and compare second field with your "keyvalue".

EDIT: faster/more efficient

edited Nov 21, 2016 at 15:25

answered Nov 21, 2016 at 15:22

Peter Majko

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Joseph Wahba Over a year ago

Thanks!. That's what I wanted to know :)

francisco sollima · Accepted Answer · 2016-11-21 15:17:34Z

1

your_dict = {'a': 1, 'b': 2, 'c': 'asd'}  # the dictionary
your_value = 'asd'  # the value to look for
[elem for elem in your_dict.iteritems() if elem[1] == 'asd']  # look for entry with value == your_value
Output: [('c', 'asd')]

EDIT:

for a list:

your_list = [['a', 1], ['b', 2], ['c', 'asd']]  # the list
your_value = 'asd'  # the value to look for
[elem for elem in your_list if elem[1] == 'asd']  # look for element with value == your_value
Output: [('c', 'asd')]

edited Nov 21, 2016 at 15:17

answered Nov 21, 2016 at 15:14

francisco sollima

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1 Comment

bruno desthuilliers Over a year ago

The op's data is a list of lists, not a dict.

bruno desthuilliers · Accepted Answer · 2016-11-21 15:27:10Z

0

I assume you're looking for the key (or keys) associated with a given value.

If your data is garanteed to be a list of (key, value) pairs, depending on 1/ the data's volume and 2/ how many lookups you'll have to perform on a same dataset, you can either do a plain sequential search:

def slookup(lst, value):
    return [k for k, v in lst if v == value]

or build a reverse index then lookup the index:

import defaultdict
def index(lst):
    d = defaultdict(list)
    for k, v in lst:
        d[v].append(k)
    return d

rindex = index(lst)
print rindex.get(someval)
print rindex.get(someotherval)

This second solution only makes sense if you have a lot of lookups to do on the same dataset, obviously...

answered Nov 21, 2016 at 15:27

bruno desthuilliers

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