Question

我想用Python完成这项任务。

您将获得一个包含交易列表的示例CSV文件。

第一列是钱来自的人的帐号，
第二列是金额，
第三栏是钱的人的帐号。

您的任务是解析CSV，并计算每个帐号的当前余额。

提交一个接受单个参数的python脚本（事务CSV文件的位置），并打印出每个帐户的余额。

CSV文件格式：

from, amount, to
314, 470.21, 275
12, 1788.98, 149
316, 2949.53, 314
5, 2193.48, 454
314, 1402.76, 371
82, 1212.1, 4420

我使用以下代码呈现此CSV文件：

import csv

def csv_data(path):
    with open(path) as csv_file:
        readCSV = csv.DictReader(csv_file)

        for line in readCSV:
            col_from = line['from']
            col_to = line['to']
            col_amount = line['amount']
            print(col_from, col_amount, col_to)

csv_data('transactions.csv')

如何计算每个帐户的当前余额？

每个帐户都进行了多笔交易。

例如：如果帐号314在from列中，则会将给定金额发送到to列中的帐号。如果在from列中找到此帐号，则必须添加以前的余额。

如何在for循环中进行这些计算？

Answer 1

这可能不是一个理想的答案，但您可以使用pandas。

import pandas as pd

df = pd.read_csv('/path/to/the/file')
total_for_each_account = [df[df['from'] == account]['amount'].sum() for account in df.from.unique()]

返回from列中每个唯一帐户的总和列表。

Answer 2

您可以按照@MrPyCharm的建议使用pandas。如果你需要clear-python解决方案wuthout额外的依赖项，你可以这样做：

data = [
    [314, 470.21,  275],
    [12,  1788.98, 149],
    [316, 2949.53, 314],
    [5,  2193.48, 454],
    [314, 1402.76, 371],
    [82, 1212.1,  420],
]

balances = {}
for from_, value, to_ in data:
    balances[from_]  = - value + balances.get(from_, 0) 
    balances[to_]  = value + balances.get(to_, 0) 

for user_id, balance in balances.items():
    print('Id: {}, balance: {}'.format(user_id, balance))

输出：

Id: 314, balance: 1076.5600000000002
Id: 275, balance: 470.21
Id: 12, balance: -1788.98
Id: 149, balance: 1788.98
Id: 316, balance: -2949.53
Id: 5, balance: -2193.48
Id: 454, balance: 2193.48
Id: 371, balance: 1402.76
Id: 82, balance: -1212.1
Id: 420, balance: 1212.1

Answer 3

我建议使用dictionary，其中键代表帐号。

import csv

def csv_data(path):

    accounts = {}  # storage of the account balances

    with open(path) as csv_file:
        readCSV = csv.DictReader(csv_file)

        for line in readCSV:
            account_from = int(line['from'])
            account_to = int(line['to'])
            transaction_amount = float(line['amount'])

            # subtract from old account
            if account_from in accounts:
                accounts[account_from] -= transaction_amount
            else:
                accounts[account_from] = (0-transaction_amount)

             # add to new account
             if account_to in accounts:
                accounts[account_to] += transaction_amount
             else:
                accounts[account_to] = transaction_amount

    for account in accounts:
        print("{}: \t{}".format(account, accounts[account]))

csv_data('transactions.csv')

以下输出：

420:    1212.1
5:      -2193.48
454:    2193.48
371:    1402.76
12:     -1788.98
82:     -1212.1
275:    470.21
149:    1788.98
314:    1076.56
316:    -2949.53

请注意，交易应始终遵循ACID-Properties。

计算python中帐户的当前余额

3 个答案: