Python:无法保存到 CSV

Question

我有一个从 API 中提取信息的脚本，应该将其写入我在同一目录中的 CSV 文件。出于某种原因，所有代码似乎都可以正常执行，但 CSV 实际上从未包含任何数据。我错过了一些重要的东西吗？我已经检查了 CSV 模块的文档，但找不到任何内容。

这是我的代码:

import time, json, requests, csv

with open('data.csv', 'w') as csvfile:
    fieldnames = ['time','last','vwap','high','low','open','vol']
    writer = csv.DictWriter(csvfile, fieldnames=fieldnames)

    writer.writeheader()

    def btstampTime():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['timestamp']

    def btstampLast():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['last']

    def btstampVWAP():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['vwap']

    def btstampHigh():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['high']

    def btstampLow():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['low']

    def btstampOpen():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['open']

    def btstampVol():
        bitStampTick = requests.get('https://www.bitstamp.net/api/ticker/')
        return bitStampTick.json()['volume']


    while True:
        timestamp = btstampTime()
        last = float(btstampLast())
        vwap = float(btstampVWAP())
        high = float(btstampHigh())
        low = float(btstampLow())
        open = float(btstampOpen())
        vol = float(btstampVol())

        writer.writerow({'time': timestamp,
                         'last': last,
                         'vwap': vwap,
                         'high': high,
                         'low': low,
                         'open': open,
                         'vol': vol})

        print('Time: ', timestamp)
        print('Last =', last)
        print('VWAP =', vwap)
        print('High =', high)
        print('Low =', low)
        print('Open =', open)
        print('Volume =', vol)
        print('')

        time.sleep(60)

Answer 1

这是有效的(和优化的 :))解决方案。请记住，信息将写入文件，但操作系统可能不会实时更新文件大小。

import os
import csv
import time
import requests

csv_file = open('data.csv', 'w')
field_names = ['time', 'last', 'vwap', 'high', 'low', 'open', 'vol']
writer = csv.DictWriter(csv_file, fieldnames=field_names)
writer.writeheader()

while True:
    info = requests.get('https://www.bitstamp.net/api/ticker/').json()
    writer.writerow({'time': info['timestamp'],
                     'last': info['last'],
                     'vwap': info['vwap'],
                     'high': info['high'],
                     'low' : info['low'],
                     'open': info['open'],
                     'vol' : info['volume']})
    csv_file.flush()
    os.fsync(csv_file.fileno())
    time.sleep(60)

    # this line is optional, you can delete it.
    print('Info appended.')