r - 错误: incompatible size when mutating in dplyr

Question

我在使用 dplyr 中的 mutate 函数时遇到问题，错误提示:

Error: incompatible size (0), expecting 5 (the group size) or 1

之前有一些帖子，我尝试了一些解决方案，但我的案例没有运气。

group-factorial-data-with-multiple-factors-error-incompatible-size-0-expe

r-dplyr-using-mutate-with-na-omit-causes-error-incompatible-size-d

grouped-operations-that-result-in-length-not-equal-to-1-or-length-of-group-in-dp

这是我尝试过的，

ff <- c(seq(0,0.2,0.1),seq(0,-0.2,-0.1))
flip <- c(c(0,0,1,1,1,1),c(1,1,0,0,0,0))
df <- data.frame(ff,flip,group=gl(2,6)) 

> df
     ff flip group
1   0.0    0     1
2   0.1    0     1
3   0.2    1     1
4   0.0    1     1
5  -0.1    1     1
6  -0.2    1     1
7   0.0    1     2
8   0.1    1     2
9   0.2    0     2
10  0.0    0     2
11 -0.1    0     2
12 -0.2    0     2

我想根据以下条件添加名为 c1 和 c2 的新组

 dff <- df%>%
      group_by(group)%>%
      mutate(flip=as.numeric(flip),direc=ifelse(c(0,diff(ff))<0,"backward","forward"))%>%
      spread(direc,flip)%>%
      arrange(group,group)%>%
      mutate(c1=ff[head(which(forward>0),1)],c2=ff[tail(which(backward>0),1)])

Error: incompatible size (0), expecting 5 (the group size) or 1

我还添加了 do 并尝试过

do(data.frame(., c1=ff[head(which(.$forward>0),1)],c2=ff[tail(which(.$backward>0),1)]))

Error in data.frame(., c1 = ff[head(which(.$forward > 0), 1)], c2 = ff[tail(which(.$backward > : arguments imply differing number of rows: 5, 1, 0

但是当我只mutate c1列时，一切似乎都正常。为什么？

Answer 1

只是扩展@allistaire的评论。

1. 您指定的条件是导致错误的原因。具体来说，tail(which(backward>0),1)
2. 可以优化给定的代码以消除 spread()

你可以试试

dff <- df%>%
  group_by(group)%>%
  mutate(flip=as.numeric(flip),direc=ifelse(c(0,diff(ff))<0,"backward","forward"))%>%
  arrange(group)%>%
  mutate(c1=ff[head(which(direc=="forward" & flip > 0),1)])

<小时/>

您似乎正在寻找识别流入点，其中 direction更改，对于每个 group 。在这种情况下，请明确说明翻转是如何相关的，或者如果您更改 flip <- c(c(0,0,1,1,1,1),c(1,1,0,0,0,0))至flip <- c(c(0,0,1,1,1,1),c(1,1,0,1,1,1))这样flip标记向 ff 方向变化，您可以使用

dff <- df%>%
  group_by(group)%>%
  mutate(flip=as.numeric(flip),direc=ifelse(c(0,diff(ff))<0,"backward","forward"))%>%
  arrange(group)%>%
  mutate(c1=ff[head(which(direc=="forward" & flip > 0),1)]) %>%
  mutate(c2=ff[tail(which(direc=="backward"& flip >0),1)])

给出:

Source: local data frame [12 x 6]
Groups: group [2]

      ff  flip  group    direc    c1    c2
   <dbl> <dbl> <fctr>    <chr> <dbl> <dbl>
1    0.0     0      1  forward   0.2  -0.2
2    0.1     0      1  forward   0.2  -0.2
3    0.2     1      1  forward   0.2  -0.2
4    0.0     1      1 backward   0.2  -0.2
5   -0.1     1      1 backward   0.2  -0.2
6   -0.2     1      1 backward   0.2  -0.2
7    0.0     1      2  forward   0.0  -0.2
8    0.1     1      2  forward   0.0  -0.2
9    0.2     0      2  forward   0.0  -0.2
10   0.0     1      2 backward   0.0  -0.2
11  -0.1     1      2 backward   0.0  -0.2
12  -0.2     1      2 backward   0.0  -0.2