使用do.call合并R中的多个csv文件 [英] merging multiple csv files in R using do.call

问题描述

我正在尝试使用以下代码导入和合并一组csv文件，但似乎没有将by = c("X"，"Y")参数传递给合并函数.有关如何解决此问题的任何建议?谢谢

I am trying to import and merge a set of csv files using the following code, but it doesn't seem to be passing the by=c("X","Y") argument to the merge function. Any recommendations on how to fix this? Thank you

csvfiles <- list.files(path = ".", pattern='bbg_.*\\.csv$')
csvfiles <- paste("fx/",csvfiles,sep="")
csvfiles

my.df <- do.call("merge",list(lapply(csvfiles, read.csv, header = TRUE), by=c("date","fx_code")))

推荐答案

merge不接受超过2个data.frame，因此您不能使用do.call将其传递给更大的列表:

merge doesn't accept more than 2 data.frames, so you can't pass it a larger list using do.call:

do.call(merge, list(iris, iris, iris))
#Error in fix.by(by.x, x) : 
#  'by' must specify one or more columns as numbers, names or logical

改为使用Reduce:

Reduce(function(x, y) merge(x, y, by="Species"), list(iris, iris, iris))
#works

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