R-'NA'文本被视为N/A [英] R - 'NA' text treated as N/A

问题描述

我在R中有一个数据框，其中包含国家/地区代码.纳米比亚的iso代码恰好是"NA". R将此文本"NA"视为N/A.

I have a data frame in R including country iso codes. The iso code for Namibia happens to be 'NA'. R treats this text 'NA' as N/A.

例如，下面的代码为我提供了纳米比亚这一行.

For example the code below gives me the row with Namibia.

test <- subset(country.info,is.na(country.info$iso.code))

我最初认为这可能是一个因素问题，所以我确保iso代码列是字符.但这没有帮助.

I initially thought it might be a factor issue, so I made sure the iso code column is character. But this didn't help.

如何解决?

推荐答案

这可能与您读取数据的方式有关.仅仅因为它的字符并不意味着您的"NA"不是NA，例如:

This probably relates to how you read in the data. Just because it's character doesn't mean your "NA" isn't an NA, e.g.:

z <- c("NA",NA,"US")
class(z)
#[1] "character"

您可以通过向我们提供(部分)数据的dput()来确认这一点.

You could confirm this by giving us a dput() of (part of) your data.

当您读入数据时，请尝试将na.strings = "NA"(例如，在read.csv中)更改为其他内容，以查看其是否有效.

When you read in your data, try changing na.strings = "NA" (e.g., in read.csv) to something else and see if it works.

例如，使用na.strings = "":

read.table(text="code country
NA  Namibia
GR  Germany
FR  France", stringsAsFactors=FALSE, header=TRUE, na.strings="")
#   code country
# 1   NA Namibia
# 2   GR Germany
# 3   FR  France

请确保检查使用""不会导致更改任何其他内容.否则，您可以使用在文件中绝对不会出现的字符串，例如"z_z_z"或类似的名称.您可以将text=..替换为文件名.

Make sure to check that the use of "" doesn't result in changing anything else. Else, you can use a string that will definitely not occur in your file like "z_z_z" or something like that.. You can replace the text=.. with your file name.

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