在Python中读取从JSON字符串解析的嵌套对象

Question

I have the following JSON string and it is not as straightforward as I would like. I am hoping for a bit of help. I need to iterate over each entry comparing it to another set of values that are also in a JSON string (which is structured much easier for me). I am looking for a suggested pattern getting the data out and using it in a compare and then if it's the result I want - print it.

The JSON:

{"success":true,
"message":"",
"result":
     {"buy":
            [
             {"Quantity":2.40078779,"Rate":1.11811290},  
             {"Quantity":0.00085042,"Rate":1.11584924} ....

And so on. There aa LOT of values. The way I am getting at the data is like this:

print ("Buy: ",b1['result']['buy'][0]['Quantity'], ",",b1['result']['buy'][0]['Rate'])

It's the middle [0] this is getting me - I can imagine I could get the number of entries, then loop through i = 0 to range(number of entries) but it really throws my logic off as the other JSON strings with entries I am comparing are structured much easier:

example of the easy (for me) JSON entry:

{
    "eth_btc":{
        "asks":[
            [105,1],
            [105.5,15],
            [104.504,0.425],
            [105.505,0.1]
        ],
        "bids":[
            [109,6],
            [113.082,0.46540304],
            [104.91,0.99007913],
            [106.83,0.07832332]
        ]
    }
}


for asks in easyJson['eth_btc']['asks']:
    print (asks)

I need to compare this asks value which is easy to iterate over against the rate value in the above string. Since the structure is different (and I am learning Python as a hobby) I cannot wrap my head around the best way to iterate through these sets of data structured differently. The datasets will be LARGE, comparing 4000 or so values living in 5 sets of data against each other, ONE BY ONE, to find the just the right pair based on my criteria.

Should I normalize all of the data FROM JSON into something else, then do my comparisons there? This is a 5 way compare with thousands of values.

pseudo - code:

If ask1 < bid2 then if volume of ask1 is <= volume of bid2 then do something
   etc - then ask1 vs bid3, and so on..
       ask2 vs bid1, ask2 vs bid3 ...
          ask3 vs bid1, ask3 vs bid2, ask3 vs bid4 ...

Apologies if this isn't clear. I am trying to tackle this project head on and I feel like I am brute forcing it and not using the power of Python and I want to learn!!!!

Thanks for any help - direction - anything !

Answer 1

I have sorted out the first part of the question - how to get at the data I was interested in:

import json
b="""{"success":true,"message":"","result":{"buy":[{"Quantity":6.67178734,"Rate":0.01390041},{"Quantity":244.11602480,"Rate":0.01386500},{"Quantity":34.17058305,"Rate":0.01385014},{"Quantity":48.76276808,"Rate":0.01383242},{"Quantity":2.00000000,"Rate":0.01383239},{"Quantity":0.07212509,"Rate":0.01383000},{"Quantity":256.05669876,"Rate":0.01381066},{"Quantity":75.00000000,"Rate":0.01381065},{"Quantity":0.12796429,"Rate":0.01381050},{"Quantity":11.51657190,"Rate":0.01381048},{"Quantity":0.07895698,"Rate":0.01381047},{"Quantity":1.00000000,"Rate":0.01380653},{"Quantity":1.07501432,"Rate":0.01380650},{"Quantity":22.18832778,"Rate":0.01380474}]}}
"""
b1 = json.loads(b)
buy = list(b1['result']['buy'])
for item in buy:
    print ("Rate: ",item['Rate'], "Quantity: ",item['Quantity'])

I needed to create a list for the data I needed - otherwise I could not figure out how to iterate through it cleanly. If there is a better way of doing this, please advise. I would rather not take DICT object and cast it into a list, but otherwise the way this data is formatted I couldn't figure out how to cleanly iterate through it.