R - subsetting a data frame in a for loop

Question

im trying to subset a data frame in a for loop to create a smaller data.frame. This is my data.frame

day      rain in mm     temperature in °C     season     
1        201            20                    summer
2        156            18                    summer
3        56             -4                    winter
4        98             15                    spring

I want to extract a data.frame for each season (with all columns). Here is my code:

for (season in seasons){
  a<- weather[which(weather$season %in% season[1]) , ,drop=TRUE]
  ... 
}

Unfortunately, the sub-setting doesn' t work. When i use a<- weather[which(weather$season %in% "summer") , ,drop=TRUE] it works perfectly. Also this does not work properly:

season <- "summer"
a<- weather[which(weather$season %in% season[1]) , ,drop=TRUE]

Does anyone see the problem with my code? Thank you.

Answer 1

It works with dplyr.

library(dplyr)
mydf <- data.frame(day = c(1,2,3,4),
                   rain = c(201,156,56,98),
                   temperature = c(20,18,-4,15),
                   season = c("summer", "summer", "winter", "spring"))
seasons <- c("spring", "summer", "autumn", "winter")
for (sea in seasons) {
  a <- dplyr::filter(mydf, season == sea)
  print(a)
}