在 R 中循环使用相同语句的大量 CSV 文件？答案

【问题标题】：Loop over a large number of CSV files with the same statements in R?在 R 中循环使用相同语句的大量 CSV 文件？
【发布时间】：2021-06-08 13:25:14
【问题描述】：

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【问题讨论】：

标签： r list loops csv

【解决方案1】：

这是读取所有文件并对其进行处理的一种方法。未经测试的代码，因为您没有给我们任何工作。

# 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"]]

【讨论】：