问题描述
我最近尝试根据两个变量（以下条件1和结果1）匹配数据框中的相邻相同的行。我见过有人对所有行都执行此操作，而不是对相邻行执行此操作，这就是为什么我开发了以下三步变通方法（我希望不要过分考虑）的原因：
-我滞后了想要进行匹配的变量。
-我比较了变量和滞后变量
Case <- c("Case 1","Case 2","Case 3","Case 4","Case 5")
Condition1 <- c(0,1,1)
Outcome1 <- c(0,1)
mwa.df <- data.frame(Case,Condition1,Outcome1)
new.df <- mwa.df
Condition_lag <- c(new.df$Condition1[-1],0)
Outcome_lag <- c(new.df$Outcome1[-1],0)
new.df <- cbind(new.df,Condition_lag,Outcome_lag)
new.df$Comp <- 0
new.df$Comp[new.df$Outcome1 == new.df$Outcome_lag & new.df$Condition1 == new.df$Condition_lag] <- 1
new.df <- subset(new.df,Comp == 0)
new.df <- subset(new.df,select = -c(Condition_lag,Outcome_lag,Comp))
这很好。但是当我尝试为此创建函数时，因为我必须对大量数据帧执行此操作，所以遇到了滞后不起作用的问题（即未执行condition_lag <- c(new.df$condition[-1],0)和outcome_lag <- c(new.df$outcome[-1],0)操作）。功能代码为：
FLC.Dframe <- function(old.df,condition,outcome){
new.df <- old.df
condition_lag <- c(new.df$condition[-1],0)
outcome_lag <- c(new.df$outcome[-1],0)
new.df <- cbind(new.df,condition_lag,outcome_lag)
new.df$comp <- 0
new.df$comp[new.df$outcome == new.df$outcome_lag & new.df$condition == new.df$condition_lag] <- 1
new.df <- subset(new.df,comp == 0)
new.df <- subset(new.df,select = -c(condition_lag,outcome_lag,comp))
return(new.df)
}
关于使用该功能，我写了new.df <- FLC.Dframe(mwa.df,Outcome1)。
有人可以帮我吗？预先非常感谢。
解决方法
只需生成游程长度ID并删除重复项即可。
with(mwa.df,mwa.df[!duplicated(data.table::rleid(Condition1,Outcome1)),])
输出
Case Condition1 Outcome1
1 Case 1 0 0
2 Case 2 1 0
3 Case 3 0 0
5 Case 5 1 1
如果您想要一个功能，那么
FLC.Dframe <- function(df,cols) df[!duplicated(data.table::rleidv(df[,cols])),]
像这样调用此函数
> FLC.Dframe(mwa.df,c("Condition1","Outcome1"))
Case Condition1 Outcome1
1 Case 1 0 0
2 Case 2 1 0
3 Case 3 0 0
5 Case 5 1 1
函数的主要问题与$的错误使用有关。该操作员按原样对待RHS输入。例如，在此行new.df$condition中，$运算符试图在new.df中找到一个名为"condition"的列，但找不到"Condition1"的列，它是{的值{1}}。如果您按照以下方式重写函数，那么它将起作用。
condition您还需要这样称呼它（请注意，您需要使用字符作为输入）
FLC.Dframe <- function(old.df,condition,outcome){
new.df <- old.df
condition_lag <- c(new.df[[condition]][-1],0)
outcome_lag <- c(new.df[[outcome]][-1],0)
new.df <- cbind(new.df,condition_lag,outcome_lag)
new.df$comp <- 0
new.df$comp[new.df[[outcome]] == new.df[["outcome_lag"]] & new.df[[condition]] == new.df[["condition_lag"]]] <- 1
new.df <- subset(new.df,comp == 0)
new.df <- subset(new.df,select = -c(condition_lag,outcome_lag,comp))
return(new.df)
}