子集根据R中第一行值设置数据框列

Question

我有一个名为ff的单行数据帧。

A   B   C   D   E   F
2   5   9   1   7   6

当a列等于7时，如何创建单列数据帧(ColContribs)

E
7

就像这样..？我用的是

ColContribs <- ff[,ff[1,]==7]

但是我得到了这个错误

Error in Ops.data.frame(ff[1, ], ColContribs) : 
‘==’ only defined for equally-sized data frames

保罗

Answer 1

我试着创建一个类似的案例，结果如下所示。

library(tidyverse)

a <- 2
e <- 7

lol <- cbind(a,e) %>% data.frame() 

ColContribs <- lol[,lol[1,]==7] %>% data.frame()

Answer 2

ff <- data.frame(A = 2, B = 5, C = 9, D = 1, E = 7, F = 6)

ColContribs <- ff[,ff[1,] == 7, drop = FALSE]

因为它是单元素数据框，所以需要指定drop == FALSE