使用dataframe进行聚集在lappy之后的行为不同

当我应用

lappy

时，我的数据集和

gather

（来自

dplyr

）中的某些更改不起作用。下面是一个最低限度的工作示例：

employee<- c('John','Peter','Mary',"Kate")
salarypre <- c(-1,23.5,33.2,34)
salarypost <- c(51,25.2,53,24.3)
startdate <- as.Date(c('2010-11-1','2008-3-25','2007-3-14','2008-3-12'))
mydata<-data.frame(employee,salarypre,salarypost,startdate)
mydata.big<-gather(mydata,feature,val,salarypre,salarypost)
View(mydata.big)

但是，现在我无法使用“聚集”：

> mydata.big<-gather(mydata,feature,val,salarypre,salarypost)
Error: is.character(x) is not TRUE

>mydata.biglapply返回一个列表，用data.frame函数将其包装以进行转换，然后聚集应按预期工作：

mydata <- data.frame(lapply(mydata, function(x) ifelse(is.numeric(x) & x < 0, NA, x)))

gather(mydata, feature, val, salarypre, salarypost)

#   employee startdate    feature  val
# 1        1     14914  salarypre   NA
# 2        4     13963  salarypre 23.5
# 3        3     13586  salarypre 33.2
# 4        2     13950  salarypre 34.0
# 5        1     14914 salarypost 51.0
# 6        4     13963 salarypost 25.2
# 7        3     13586 salarypost 53.0
# 8        2     13950 salarypost 24.3

mydata%
聚集（特征、val、salarypre、salarypost）

mydata <- data.frame(lapply(mydata, function(x) ifelse(is.numeric(x) & x < 0, NA, x)))

gather(mydata, feature, val, salarypre, salarypost)

#   employee startdate    feature  val
# 1        1     14914  salarypre   NA
# 2        4     13963  salarypre 23.5
# 3        3     13586  salarypre 33.2
# 4        2     13950  salarypre 34.0
# 5        1     14914 salarypost 51.0
# 6        4     13963 salarypost 25.2
# 7        3     13586 salarypost 53.0
# 8        2     13950 salarypost 24.3

myFun <- function(x){ifelse(x < 0, NA, x)}

mydata %>% mutate_if(is.numeric, myFun) %>% 
  gather(feature, val, salarypre, salarypost)