"NA"字符串转换为<NA>

Question

我有一个csv国家名称及其iso代码的文件.这是它的样子:

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

我data.frame使用以下代码阅读它:

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

这是数据的样子:

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

即使我明确设置 ,字符串"NA"也会转换为.<NA>colClasses = c("character")

我如何"NA"展示作为"NA"的data.frame？

Answer 1

尝试na.strings明确设置参数 - 默认为"NA":

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