Using lapply to apply a function over list of data frames and saving output to files with different names
Solution 1
It will work with the following lapply
call:
lapply(names(mylist), function(x) NewVar(mylist[[x]], "y", x))
Solution 2
There are many options. For example:
lapply(names(mylist),
function(x)write.csv(mylist[x],
file =paste0(x,'.csv')))
or using indexes :
lapply(seq_along(mylist),
function(i)write.csv(mylist[i],
file =paste0(names(mylist)[i],'.csv')))
user2414840
Updated on December 18, 2020Comments
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user2414840 over 3 years
I have a list of data frames and have given each element in the list (e.g. each data frame) a name:
e.g.
df1 <- data.frame(x = c(1:5), y = c(11:15)) df2 <- data.frame(x = c(1:5), y = c(11:15)) mylist <- list(A = df1, B = df2)
I have a function that I want to apply to each data frame; In this function, I want to include a line to write the results to file (eventually I want to do more complicated things like save plots of the correlation between two variables for each data frame but thought I'd start simple)
e.g.
NewVar <- function(mydata, whichVar, i) { mydata$newVar <- mydata[, whichVar] + 1 write.csv(mydata, file = i) }
I want to use
lapply()
to apply this function to each data frame in my listsomething like:
hh<-lapply(mylist, NewVar, whichVar = "y")
I can't figure out how to assign the "i" within the context of lapply so that
i
iterates over the names in the list of data frames, saving multiple files with different names (in this case, two files namedA
andB
) that correspond with the modified data frames.