更改R中字段的名称

Question

我是这个组的新成员(也是一个新的R用户)，我有一个问题.我有一个像这样的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  

问题是如何更改列V2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”在新的专栏中以“金融”和“私营部门工业”和“公共部门工业”作为“非金融”。希望我说得够清楚了。非常感谢你的帮助。

Answer 1

假设您的dataframe名为df，您可以执行如下操作：

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，如果您确信您的V2字段中包含"bank“和"industrial”两个词，那么您就可以这样决定如何在新列中调用这些值：

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

这与数据表的工作方式是一样的。

Answer 2

在这个场景中，替换()非常方便。假设数据为DF，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 3

如果DT是你的data.table

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

规范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")]

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