如何删除R中数据帧的每第n行?
您可以创建如下函数
Nth.delete<-function(dataframe, n)dataframe[-(seq(n,to=nrow(dataframe),by=n)),]
我们来试试吧
DF<-data.frame(A=1:15, B=rnorm(15), C=sample(LETTERS,15))
Nth.delete(DF, 3)
如果你想从数据框或向量等获取每个第n列,请使用模数子集...
通过在此处重复集合作为3的模数来选择第n列(根据需要选择第n个)
> x <- c(1,2,3,4,5,6)
> d <- rbind(x,x,x)
> df <- as.data.frame(d, row.names=T)
> c <- 1:ncol(df)
> c
[1] 1 2 3 4 5 6
c%%3 ### nth cycle, here every 3
[1] 1 2 0 1 2 0
#select the every 3rd column of every 3
> df[, c%%3==0]
V3 V6
1 3 6
2 3 6
3 3 6
#every first column of every 3
> df[, c%%3==1]
V1 V4
1 1 4
2 1 4
3 1 4
#every 2nd column of every 3
> df[, c%%3==2]
V2 V5
1 2 5
2 2 5
3 2 5
#drop the 3rd columns
> df[, !(c%%3==0)]
V1 V2 V4 V5
1 1 2 4 5
2 1 2 4 5
3 1 2 4 5
etc ...交换c <-nrow(df)以对行进行子集化
我希望使用tidyverse
运算符添加%%
样式方法来解决这个问题。
library(dplyr)
df <- data.frame(V1 = seq(26), V2 = letters)
df %>% dplyr::filter(row_number() %% 2 != 0) ## Delete even-rows
df %>% dplyr::filter(row_number() %% 2 != 1) ## Delete odd-rows
df %>% dplyr::filter(row_number() %% 3 != 1) ## Delete every 3rd row starting from 1
当然,您可以使用相同的想法来选择每个第n行。见here