Multiple data frame handling - r

Question

I have several data frames and they were named like this
plant1_wd_hrly, plant2_wd_hrly,plant3_wd_hrly......,
Each of them have data like this :
time temp
1 2012-01-01 00:00:00 20
2 2012-01-01 01:00:00 21
3 2012-01-01 02:00:00 22
4 2012-01-01 03:00:00 23
5 2012-01-01 04:00:00 24
I need to do a aggregation to the daily level with all of them and also calculate the daily max, min.
Here is the code to generate such df:
x=seq(
from=as.POSIXct("2012-1-1 0:00", tz="UTC"),
to=as.POSIXct("2012-1-3 23:00", tz="UTC"),
by="hour")
plant1_wd_hrly=data.frame("time"=x,"temp"=seq(20,length.out=length(x)))
plant1_wd_hrly$time=as.POSIXct(substr(plant1_wd_hrly$time,1,10))
plant2_wd_hrly=data.frame("time"=x,"temp"=seq(25,length.out=length(x)))
plant2_wd_hrly$time=as.POSIXct(substr(plant1_wd_hrly$time,1,10))
plant1_wd_hrly$temp[2:3]=NA
plant2_wd_hrly$temp[5:6]=NA
If it is only one df I usually do the aggregation using dplyr package:
plant1_hrly=plant1_wd_hrly %>% group_by(time) %>% summarise(
temp_avg = mean(temp,na.rm=TRUE),
temp_max = max(temp,na.rm=TRUE),
temp_min = min(temp,na.rm=TRUE))
But with multiple df, what is a more efficient way to do this?
First thing I'm thinking is to do a for loop, could I load a dymanic generated variable name from R, so I could loop through the different df since they all have very similar names? If I want to assign a value to a dynamic generated variable name I could use assign, but how to load one?
Thank you.

Answer 1

Make a vector of df names like that, for instance:
df_names <- grep("plant", ls(), value = T)
If no other variable names contain "plant". Otherwise you need to play with regex. Or pick them by hand.
Then just loop over the names using get() and assign() in the body.
You give the first one the name as a string, and it get the value from the variable. The second takes a name and a value and assign the value to the name.
for(df_n in df_names){
temp_data = get(df_n) %>% group_by(time) %>% summarise(
temp_avg = mean(temp,na.rm=TRUE),
temp_max = max(temp,na.rm=TRUE),
temp_min = min(temp,na.rm=TRUE))
assign(paste0(df_n, "_agr"), temp_data)
}