使用tidyr :: complete with group_by [英] Using tidyr::complete with group_by

问题描述

有没有人知道 tidyr :: complete（）是否支持通过 group_by（）进行分组？

Does anyone know if tidyr::complete() supports grouping via group_by()?

确切地说：我有一些数据框看起来像这样

To be precise: I have some data frame that looks like this

df <- data.frame(
  "ID"   = rep(1:2, each = 2),
  "Col1" = c("A", NA, "AA", NA),
  "Col2" = c("B", "C", "BB", "CC"))

现在我想使用 complete（）和 group_by（）来计算所有可能的组合每个组！

Now i'd like to use complete() and group_by() to compute all possible combinations per group!

df %>% 
 group_by(ID) %>% 
 complete(Col1, Col2)

  Error in .Call("dplyr_left_join_impl", PACKAGE = "dplyr", x, y, by_x,  : 
  negative length vectors are not allowed

这会导致错误，但是，使用 complete（）而不进行分组，我想要的。

This causes an error. However, using complete() without grouping works but thats not what i want.

df %>% 
 complete(Col1, Col2)

问题：

1. / code>完成（）根本不适用于 group_by ？


2. 如果是这样，我该怎么做（最好不用循环）？

1. Have I done anything wrong, or does complete() simply not work with group_by?
2. If so, how could I do this instead (preferably without using a loop)?

推荐答案

您可以使用完成和 group_by ，但您必须使用 do 语句：

You could do it using complete and group_by, but you have to use a do statement:

df %>% 
 group_by(ID) %>% 
 do(complete(., Col1, Col2, fill = list(ID = .$ID)))

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