在虚拟机上按条件在数据帧行中添加列总和 [英] Adding columns sums in dataframe row wise conditional on a dummy

问题描述

我想一次添加一行数据框各列的总和，但要以具有二进制变量的另一列为条件.

I would like to add the sums of the columns of my dataframe one row at a time, conditional on another column that has a binary variable.

因此，对于每一行，我想为所有行(对应行中的二进制变量具有相同的值)计算其上方整列的总和.

So for each row, I would like to compute the sum of the entire column above it for all rows where the binary variable in the corresponding row has the same value.

这里是一个例子:

dummy var1  var2
1     x1     y1
0     x2     y2
0     x3     y3
1     x4     y4

我的目标是获得这个:

dummy var1     var2
1     x1       y1
0     x2       y2
0     x3+x2    y3+y2
1     x4+x1    y4+y1

我之前曾问过这个问题的简化版本(在datawise rowwise )，我只是在没有条件的情况下添加了以上所有值.有没有办法合并这种情况?

I have asked this question previously for a simplified version (Adding columns sums in dataframe row wise) where I just add all of the values above without the condition. Is there a way to incorporate this condition?

推荐答案

data.table::rleid将为您提供所需的分组.如果将数据框转换为data.table，则如下所示:

data.table::rleid will give you the grouping you want. If you convert your data frame to a data.table, it's like this:

(注意:这是假设您的文本正确且示例不正确:在dummy列中按连续个相等的值分组.)

(Note: this assumes that your text is accurate and your example incorrect: it groups by consecutive equal values in the dummy column.)

library(data.table)
setDT(your_data)
your_data[, id := rleid(dummy)][
  , c("var1", "var2") := .(cumsum(var1), cumsum(var2)), by = id
]

如果需要对一堆列执行此操作，请按上述设置id，定义列向量，然后:

If you need to do this to a bunch of columns, set the id as above, define your vector of columns, and then:

cols = c("var1", "var2", "var3", ...)
your_data[, (cols) := lapply(.SD, cumsum), by = id, .SD = cols]

---

如果您只想按虚拟列分组，而忽略连续性，那么您的问题

---

If you just want to group by the dummy column, ignoring consecutiveness, then your question is an exact duplicate of this one, and you can do it like this:

setDT(your_data)
your_data[, c("var1", "var2") := .(cumsum(var1), cumsum(var2)), by = dummy]

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