如何从txt文件提取某些内容？

Question

This is my code:

import urllib.request 
import urllib.parse
x = urllib.request.urlopen('http://transport.opendata.ch/v1/connections? 
from=Baldegg_kloster&to=Luzern&fields[]=connections/from/prognosis/departure')
data = x.read()`enter code here`

saveFile = open('Ergebnis4.txt', 'w')
saveFile.write(str(data))
saveFile.close()here

When I run it, I get this:

{"connections":[{"from":{"prognosis":{"departure":"2018-06- 
07T11:52:00+0200"}}},{"from":{"prognosis":{"departure":"2018-06- 
07T12:22:00+0200"}}},{"from":{"prognosis":{"departure":"2018-06- 
07T12:53:00+0200"}}},{"from":{"prognosis":{"departure":null}}}]}

However, I only need the Datetime values without the text. How could I achieve that?

Answer 1

You can extract datetimes from the response with regex.

# ...
data = x.read()

dates = re.findall('\d{4}[^+]*\+\d{4}', str(data))
dates = '\n'.join(dates)

saveFile = open('Ergebnis4.txt', 'w')
saveFile.write(dates)
saveFile.close()

Answer 2

You are having a JSON response. You can use the JSON module.

Ex:

import json
with open('Ergebnis4.txt', 'w') as outfile:
    for i in json.loads(data)["connections"]:
        saveFile.write(i['from']['prognosis']['departure'])

Answer 3

This is how you can get that:

import requests

res = requests.get("http://transport.opendata.ch/v1/connections?from=Baldegg_kloster&to=Luzern&fields[]=connections/from/prognosis/departure")
for item in res.json()['connections']:
    print(item['from']['prognosis']['departure'])

Output:

2018-06-07T12:22:00+0200
2018-06-07T12:53:00+0200
2018-06-07T13:22:00+0200
None

Or using urllib module:

from urllib.request import urlopen
import json

res = urlopen("http://transport.opendata.ch/v1/connections?from=Baldegg_kloster&to=Luzern&fields[]=connections/from/prognosis/departure")
for item in json.load(res)['connections']:
    print(item['from']['prognosis']['departure'])