如何在R中从数据框中删除每第n行?
Nth.delete<-function(dataframe, n)dataframe[-(seq(n,to=nrow(dataframe),by=n)),]
让我们来测试一下
DF<-data.frame(A=1:15, B=rnorm(15), C=sample(LETTERS,15))
Nth.delete(DF, 3)
df[-rowNumber, ]
删除了该行。 - MySchizoBuddy我希望将 tidyverse
风格的方法应用到这个问题中,使用 %%
运算符。
library(dplyr)
df <- data.frame(V1 = seq(26), V2 = letters)
df %>% filter(row_number() %% 2 != 0) ## Delete even-rows
df %>% filter(row_number() %% 2 != 1) ## Delete odd-rows
df %>% filter(row_number() %% 3 != 1) ## Delete every 3rd row starting from 1
当然,您可以使用相同的思路来选择每n行,参见此处
> 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
等等… 替换 c<-nrow(df)
以选择行。
df[seq(1, NROW(df), by = n),]
(此代码为R语言,意为从数据框df中每隔n行选取一行。) - Ramnathdf[-seq(n,NROW(df),by=n),]
可能效果更好。 - Henry