"NA"字符串转换为< NA>

问题描述：

我有一个csv文件，其中包含国家/地区名称及其iso代码.看起来是这样的:

I have a csv file with country names and their iso codes. Here's what it looks like:

"Name","Code"
"Afghanistan","AF"
"Albania","AL"
"Algeria","DZ"
"Namibia","NA"

我使用以下代码在data.frame中阅读了该文件:

I read it in a data.frame using the following code:

cc = read.csv("countries.csv", header=TRUE, stringsAsFactors=FALSE, 
                                           colClasses = c("character"))

数据如下:

Name         Code
Afghanistan  AF
Albania      AL
Algeria      DZ
Namibia      <NA>

即使我显式设置了colClasses = c("character")，字符串"NA"也将转换为<NA>.

The string "NA" is getting converted to <NA> even though I explicitly set colClasses = c("character").

如何让"NA"在data.frame中显示为"NA"?

答

尝试显式设置na.strings参数-默认值为"NA":

Try setting the na.strings parameter explicitly - the default is"NA":

    cc = read.csv("countries.csv", header=TRUE, stringsAsFactors=FALSE,
                              colClasses = c("character"),  na.strings="" )