Question

所以我的问题是编写一个函数语句（），它将浮点数列表作为输入，正数表示存款，负数表示来自银行账户的抽取。你的函数应该返回一个两个浮点数的列表;第一个是存款的总和，第二个（负数）将是提款的总和。

我写的那个似乎是将提取空列表更改为值0，因此不允许追加功能工作。我想知道python是否有这样的原因，或者它只是一个奇怪的错误？

以下是供参考的代码：

def statement(lst):
"""returns a list of two numbers; the first is the sum of the
   positive numbers (deposits) in list lst, and the second is
   the sum of the negative numbers (withdrawals)"""
deposits, withdrawals, final = [], [], []
for l in lst:
    print(l)
    if l < 0:
        print('the withdrawals are ', withdrawals)  # test
        withdrawals.append(l)
        print('the withdrawals are ', withdrawals)  # test
    else:
        print('the deposits are', deposits)  # test
        deposits.append(l)
        print('the deposits are', deposits)  # test
    withdrawals = sum(withdrawals)
    deposits = sum(deposits)
    final.append(deposits)
    final.append(withdrawals)

Answer 1

这些行：

withdrawals = sum(withdrawals)
deposits = sum(deposits)
final.append(deposits)
final.append(withdrawals)

需要写成：

final.append(sum(deposits))
final.append(sum(withdrawals))

否则，变量withdrawals和deposits将被反弹到sum返回的整数对象。换句话说，它们将不再引用此处创建的列表对象：

deposits, withdrawals, final = [], [], []

Python将空列表更改为整数

1 个答案: