如何用 pandas 中的重复数据填写行？
问题描述：
在R中，当将不等长的新数据添加到数据帧时，值将重复以填充数据帧：
In R, when adding new data of unequal length to a data frame, the values repeat to fill the data frame:
df <- data.frame(first=c(1,2,3,4,5,6))
df$second <- c(1,2,3)
收益：
first second
1 1 1
2 2 2
3 3 3
4 4 1
5 5 2
6 6 3
但是，熊猫需要相等的索引长度。
However, pandas requires equal index lengths.
如何像在R中那样在熊猫中填充重复数据？
How do I "fill in" repeating data in pandas like I can in R?
答
似乎没有优雅的方法。这是我刚想出的解决方法。基本上创建一个比原始数据框大的重复列表，然后将其左联接。
Seems there is no elegant way. This is the workaround I just figured out. Basically create a repeating list just bigger than original dataframe, and then left join them.
import pandas
df = pandas.DataFrame(range(100), columns=['first'])
repeat_arr = [1, 2, 3]
df = df.join(pandas.DataFrame(repeat_arr * (len(df)/len(repeat_arr)+1),
columns=['second']))