更改 R 中的字段名称

Question

我是这个组的新手（也是一个全新的 R 用户），我有一个问题。我有一个这样的data.table

Date             V2                       Deal Type
-----------------

1: 2009-1       Public sector bank        Corporate Bond-Investment-Grade                 
2: 2009-1       Private sector bank       Corporate Bond-Investment-Grade                 
3: 2009-7       Private sector industrial Corporate Bond-Investment-Grade                   
4: 2009-1       Private sector bank       Corporate Bond-Investment-Grade                  
5: 2009-1       Private sector bank       Covered Bond                         
6: 2009-1       Public sector bank        Corporate Bond-Investment-Grade                 
7: 2009-1       Private sector bank       Corporate Bond-Investment-Grade  

问题是如何更改 V2 列中变量（和变量）的名称。例如，我希望“公共部门银行”和“私营部门银行”在新列中显示为“金融”和“私营部门工业”，“公共部门工业”作为“非金融”出现。希望我已经足够清楚了。非常感谢您的帮助。

Answer 1

replace() 在这种情况下会很方便。假设您的数据框为 DF，而您的新列为 V2new：

# Creating new column V2new and replacing "Public/Private sector bank" to "financial" 
DF$V2new <- replace(DF$V2 ,DF$V2 =="Public sector bank"|DF$V2=="Private sector bank","financial") 
# Replacing "Public/Private sector industrial"  from V2new to "non-financial"
DF$V2new <-  replace(DF$V2new ,DF$V2new =="Public sector industrial"|DF$V2new =="Private sector industrial","non-financial")

Answer 2

假设您的数据框称为 df，您可以执行以下操作：

df <- read.csv("data.csv", stringsAsFactors=FALSE)

df$newColumn[df$V2 == "Public sector bank" | df$V2 == "Private sector bank"] <- "financial"
df$newColumn[df$V2 == "Public sector industrial" | df$V2 == "Private sector industrial"] <- "non-financial"

或者，如果您确定您的 V2 字段中包含“银行”和“工业”这两个词，并且这就是您确定在新列中调用什么值的方式，您可以这样做：

df$newColumn[grepl("bank", df$V2)] <- "financial"
df$newColumn[grepl("industrial", df$V2)] <- "non-financial"

这同样适用于数据表

Answer 3

如果 DT 是你的 data.table

`DT[,':='(V3 = ifelse(V2 %in% c("Public sector bank","Private sector bank"),"Non financial","Financial")`]

标准化文本字段通常是一种很好的做法，因此您可以考虑：

DT[,':='(V3 = ifelse(tolower(gsub(" ","",V2)) %in% c("publicsectorbank","privatesectorbank"),"Non financial","Financial")]

希望对你有帮助，我也推荐https://s3.amazonaws.com/assets.datacamp.com/img/blog/data+table+cheat+sheet.pdf