Loop tasks by replacing one unique filename part by another - r

Question

I am new to R and have just written a code, which works fine. I would like to loop this so that it also applies to the other identical 41 data.frames.
The inputfiles are called "weatherdata.. + UNIQUE NUMBER", the output files I would like to call "df + UNIQUE NUMBER".
The code I have written applies now only to the file weatherdata..5341. I could just press CTRL + F and replace all 5341 and run which is easy to do. But could I also do this with some sort of loop? or do you have a nice tutorial for me that could teach me how to do this? I have seen a tutorial with the for-loop but I couldn't figure out how to apply it for my code.
A small part of the code is provided below! I think that if the loop works on the code given below it will also work for the rest of the code. All help appreciated! :)
#List of part of the datafiles just 4 out of 42 files
list.dat <- list(weatherdata..5341,weatherdata..5344, weatherdata..5347,
weatherdata..5350)
# add colum with date(month) as a decimal number
weatherdata..5341$Month <- format( as.Date(weatherdata..5341$Date) , "%m")
# convert to date if not already
weatherdata..5341$Date <- as.Date(weatherdata..5341$Date, "%d-%m-%Y")
#Try rename columns
colnames(weatherdata..5341)[colnames(weatherdata..5341)=="Max.Temperature"] <- "TMPMX"
# store as a vector
v1 <- unlist(Tot1)
# store in outputfile dataframe
Df5341<- as.data.frame.list(v1)

Answer 1

You can create a list of all the dataframes and then use sapply to loop through each one of them. Here is a sample code :
> v1 <- list(data.frame(x = c(1,2), y = c('a', 'b')), data.frame(x = c(3,4), y = c('c', 'd')))
> v1
[[1]]
x y
1 1 a
2 2 b
[[2]]
x y
1 3 c
2 4 d
> sapply(v1 , function(x){(x$x <- x$x/4)})
[,1] [,2]
[1,] 0.25 0.75
[2,] 0.50 1.00
Then you can replace content inside the function. Hope this helps.

Answer 2

Something like this should work:
## Assuming that your files are CSV files and are alone in the folder
Fnames <- list.files() # this pulls the names of all the files
# in your working directory
Data <- lapply(Fnames, read.csv)
for( i in 1:length(Data)){
# Put your code in here, replacing the Df names with Data[[i]]
# for example:
# add colum with date(month) as a decimal number
Data[[i]]$Month <- format( as.Date(Data[[i]]$Date) , "%m")
# convert to date if not already
Data[[i]]$Date <- as.Date(Data[[i]]$Date, "%d-%m-%Y")
#Try rename columns
colnames(Data[[i]])[colnames(Data[[i]])=="Max.Temperature"] <- "TMPMX"
# And so on..
}