How to use Sapply in multiple dataframms

Question

I have three dataframes: AAA, BBB, CCC, I want to use sapply to browse the max of each dataframe, instead of using

sapply(AAA, max)
sapply(BBB, max)
sapply(CCC, max)

I tried to use a loop to solve this function, I tried the following lines, but didn't work

dfs = list(AAA, BBB, CCC)

for(df in dfs){
  print(deparse(substitute(df)))
  print(sapply(df, max))
  readline(prompt="Press [enter] to continue")
}

I intended to use print(deparse(substitute(df))) to print out AAA, BBB, CCC. However, all I got is df.

I wonder how to fix this problem.

Or is there any other way to apply sapply to multiple dataframes at the same time?

Answer 1

We may loop over the list of data.frames and then use sapply on the dataset

lapply(dfs, \(dat) sapply(dat, max))

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Or another option is colMaxs

library(matrixStats)
lapply(dfs, \(dat) colMaxs(as.matrix(dat)))

---

If we want to print the object names, it should be a named list and then loop over either the sequence of list or the names of the list and print the names

dfs <- list(AAA = AAA, BBB = BBB, CCC = CCC)
for(nm in names(dfs)) {
   print(nm)
   print(sapply(dfs[[nm]], max))
}