Question

我想遍历所有行并重命名它们。基本上我只想在我的数据框中删除一些单词（每个行名称中的相同模式）。

代码：

for (i in rownames(df)) {

  row.names(df)[i] <- gsub("*The words I want to remove*", "", row.names(df)[i])
}

我收到以下错误：

row.names<-.data.frame中的错误（*tmp*，值= c（“我想删除的字词”，：无效的'row.names'长度

请注意，代码在循环之外工作正常。

Answer 1

你的顺序不好：

在这里，我在rownames（df）中依次是你的每个名字：

for (i in rownames(mtcars)) {
+   print(i)
+ }
[1] "Mazda RX4"
[1] "Mazda RX4 Wag"
[1] "Datsun 710"
...

所以row.names(df)[i]试图做row.names(df)["yourrowname"]，即：row.names(mtcars)["Mazda RX4"]返回NA。

您编写代码的方式，i必须是一个数字。所以：

for (i in seq_along(rownames(df))) {
  print(i)
}
[1] 1
[1] 2
[1] 3
[1] 4
[1] 5
[1] 6
[1] 7
...

现在，要替换行名，您需要对i进行双重括起来。这是mtcars的一个例子：

data("mtcars")
rownames(mtcars)
[1] "Mazda RX4"           "Mazda RX4 Wag"      
[3] "Datsun 710"          "Hornet 4 Drive"     
[5] "Hornet Sportabout"   "Valiant"            
[7] "Duster 360"          "Merc 240D"          
[9] "Merc 230"            "Merc 280"           
[11] "Merc 280C"           "Merc 450SE"         
[13] "Merc 450SL"          "Merc 450SLC"        
[15] "Cadillac Fleetwood"  "Lincoln Continental"

for (i in seq_along(rownames(mtcars))) {

  row.names(mtcars)[[i]] <- gsub(" ", "_", row.names(mtcars)[[i]])
}
rownames(mtcars)

[1] "Mazda_RX4"           "Mazda_RX4_Wag"      
[3] "Datsun_710"          "Hornet_4_Drive"     
[5] "Hornet_Sportabout"   "Valiant"            
[7] "Duster_360"          "Merc_240D"          
[9] "Merc_230"            "Merc_280"           
[11] "Merc_280C"           "Merc_450SE"         
[13] "Merc_450SL"          "Merc_450SLC"

但正如评论中所述，这里不需要for循环：

rownames(mtcars) <- gsub(" ", "_", row.names(mtcars))
rownames(mtcars)
[1] "Mazda_RX4"           "Mazda_RX4_Wag"      
[3] "Datsun_710"          "Hornet_4_Drive"     
[5] "Hornet_Sportabout"   "Valiant"            
[7] "Duster_360"          "Merc_240D"          
[9] "Merc_230"            "Merc_280"           
[11] "Merc_280C"           "Merc_450SE"         
[13] "Merc_450SL"          "Merc_450SLC"

我的for循环有什么问题？ -gsub rownames

1 个答案: