Question

我正在尝试从循环中创建多维列表，但是当为行和列输入新值时，所有列值会同时更改，导致仅保留最后一个值，这是某些事情。我知道它与我如何初始化列表有关，但是不确定如何修复它。

代码：

sellorderprices = ["Sellorderprice", 0, 1, 2, 3, 4, 5]
buyorderprices=["Buyorderprice", 10, 11, 21, 31, 41, 51]
days=["Days",150, 120, 90, 60, 30, 0]
export_data=[[None]*3]*(len(days))

for n in range (0, len(export_data)):
        export_data[n][0]=days[n]
        export_data[n][1]=buyorderprices[n]
        export_data[n][2]=sellorderprices[n]
print(export_data)

这将打印[[0，51，5]，[0，51，5]，[0，51，5]，[0，51，5]，[0，51，5]，[0，51 ，5]，[0、51、5]]

Answer 1

尝试：

export_data=[[None for i in range(3)] for i in range(len(days))]

Answer 2

创建export_data时引用的是同一列表您可以通过将代码更改为

来避免这种情况

export_data = [[None]*3 for i in range(len(days))]

或者，您可以使用zip做同样的事情

export_data = list(zip(days, buyorderprices, sellorderprices))
# [('Days', 'Buyorderprice', 'Sellorderprice'), (150, 10, 0), (120, 11, 1), (90, 21, 2), (60, 31, 3), (30, 41, 4), (0, 51, 5)]

或

export_data = [list(e) for e in zip(days, buyorderprices, sellorderprices)]
# [['Days', 'Buyorderprice', 'Sellorderprice'], [150, 10, 0], [120, 11, 1], [90, 21, 2], [60, 31, 3], [30, 41, 4], [0, 51, 5]]

Python多维列表-如果更改一个值，则列中的所有值都会更改

2 个答案: