First of all, I want to say that I am understanding how to filter the information in the Python dictionaries from a JSON and then write them in a JSON file. I take a normal workflow on the basis that we do not always know exactly what we should iterate. To illustrate a simple but real-life example.
The workflow
- Decode JSON
- Treat and process the data (convert it into information)
- Encode JSON and write them in a file
The example
For this I am using the CoinMarketCap apin and this is the data structure:
{
"data": {
"1": {
"id": 1,
"name": "Bitcoin",
"symbol": "BTC",
"website_slug": "bitcoin",
"rank": 1,
"circulating_supply": 17168112.0,
"total_supply": 17168112.0,
"max_supply": 21000000.0,
"quotes": {
"USD": {
"price": 8159.91,
"volume_24h": 6805930000.0,
"market_cap": 140090248790.0,
"percent_change_1h": -0.65,
"percent_change_24h": 5.84,
"percent_change_7d": 18.14
}
},
"last_updated": 1532445803
},
"1027": {
"id": 1027,
"name": "Ethereum",
"symbol": "ETH",
"website_slug": "ethereum",
"rank": 2,
"circulating_supply": 100891486.0,
"total_supply": 100891486.0,
"max_supply": null,
"quotes": {
"USD": {
"price": 472.418,
"volume_24h": 2187530000.0,
"market_cap": 47662953974.0,
"percent_change_1h": -1.42,
"percent_change_24h": 2.14,
"percent_change_7d": -1.83
}
},
"last_updated": 1532445813
},
"52": {
"id": 52,
"name": "XRP",
"symbol": "XRP",
"website_slug": "ripple",
"rank": 3,
"circulating_supply": 39315683476.0,
"total_supply": 99991900487.0,
"max_supply": 100000000000.0,
"quotes": {
"USD": {
"price": 0.458599,
"volume_24h": 305718000.0,
"market_cap": 18030133126.0,
"percent_change_1h": -1.22,
"percent_change_24h": 1.69,
"percent_change_7d": -5.25
}
},
"last_updated": 1532445797
},
"metadata": {
"timestamp": 1532445415,
"num_cryptocurrencies": 1664,
"error": null
}
}
As you can see are nested dictionaries and there comes a point where you can not iterate explicitly, we must do it dynamically, otherwise we should know the identification of the encryption currency.
We begin the exploration of the dictionaries:
#!/usr/bin/python3
import json
import requests
response = requests.get("https://api.coinmarketcap.com/v2/ticker/")
data = json.loads(response.text)
def keep(data):
for i in data['data'].key():
print(i)
keep(data)
As you can see, this is the complex part to iterate.
I managed to get rid of the complex part to get the Top10 of cryptocurrencies:
#!/usr/bin/python3
import json
import requests
response = requests.get("https://api.coinmarketcap.com/v2/ticker/")
data = json.loads(response.text)
def keep(data):
for i in data['data'].values():
if i['rank'] <= 10:
print(json.dumps(i, indent=4))
keep(data)
But I can not write it in a JSON file, I hope you can help me, thanks in advance.