R中的read.csv中指定colClasses的问题 [英] problem with specifying colClasses in read.csv in R

问题描述

我试图在read.csv中指定colClasses，以试图加快csv文件的读取速度.但是，我遇到以下问题:

I am trying to specify colClasses in read.csv in an attempt to speed up the reading of csv file. However, I encounter the following problem:

假设我有一个名为"t.csv"的文件:

assuming that i have a file called "t.csv":

"a","b"
"x","0"

然后，如果我在R中运行以下命令:

Then, if I run the following in R:

data <- read.csv('t.csv' , stringsAsFactors=FALSE, check.names=FALSE , comment.char='', colClasses= c('character','numeric') )

我收到此错误:

Error in scan(file, what, nmax, sep, dec, quote, skip, nlines, na.strings,  : 
  scan() expected 'a real', got '"0"'

起初，我认为这是我的报价存在问题.但是在read.csv中使用quote =''并没有帮助.

At first I thought it was the problem with my quote. But using quote='"' in read.csv didn't help.

推荐答案

您的第二列不是被引用的numeric，而是文本.

Your second column is not numeric as it is quoted -- that makes it text.

因此，将其阅读为文本，然后在该列上调用as.numeric(...).或更改文件.

So read it as text, then call as.numeric(...) on the column. Or alter the file.

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