循环使用 R 中相同语句的大量 CSV 文件？

Question

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Answer 1

Here's one way you can read all the files and proceess them. Untested code as you haven't given us anything to work on.

# Get a list of CSV files. Use the path argument to point to a folder
# other than the current working directory
files <- list.files(pattern=".+\\.csv")

# For each file, work your magic
# lapply runs the function defined in the second argument on each
# value of the first argument
everything <- lapply(
  files,
  function(f) {
    values <- read.csv(f, header=FALSE)
    apply(values, 1, function(x) length(which(x==3)))
  }
)
# And returns the results in a list.  Each element consists of 
# the results from one function call.
# Make sure you can access the elements of the list by filename
names(everything) <- files

# The return value is a list.  Access all of it with
everything

# Or a single element with
everything[["values04.csv"]]