Python根据不同的行创建新的数据框列
[英]Python create new dataframe column based on different rows
问题描述
So I am having dataframe which looks like this
所以我有看起来像这样的数据框
v1 v2
day1 x x
day2 x x
day3 x x
day4 x x
day5 x x
What I need is to add new column v3 which will be the difference "today's v1 - yesterday's v2"我需要的是添加新列 v3，这将是“今天的 v1 - 昨天的 v2”的区别
I've tried df[v3] = df[v1][1:] - df[v2][:-1]我试过df[v3] = df[v1][1:] - df[v2][:-1]
But it looks like python is somehow mapping rows by timestamp and I am receiving "today's v1 - today's v2" as result except for first and last rows which are NaN.但看起来python以某种方式按时间戳映射行，我收到“今天的v1 - 今天的v2”作为结果，除了第一行和最后一行是NaN。
1 个解决方案
解决方案1
2 已采纳 2019-12-02 13:24:32
IIUC，随着您的日子单调增加，您可以通过v2.shift()减去v1
df['v3'] = df.v1 - df.v2.shift()
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