重新排序因素在數據幀

Question

我從0到39以下因素如何，他們現在下令：

> levels(items$label) 
[1] "0" "1" "10" "11" "12" "13" "14" "15" "16" "17" "18" "19" 
[13] "2" "20" "21" "22" "23" "24" "25" "26" "27" "28" "29" "3" 
[25] "30" "31" "32" "33" "34" "35" "36" "37" "38" "39" "4" "5" 
[37] "6" "7" "8" "9" 

如何重新排序按數字順序，顯示目的？我不想改變數據框的含義。

更新：如何更新原始數據框items，排序後的因子爲labels？這不應該實質性地改變數據框;我只是希望這些因素在後續的操作中以正確的順序出來。

Answer 1

sorted_labels <- paste(sort(as.integer(levels(items$label)))) 

給出：

[1] "0" "1" "2" "3" "4" "5" "6" "7" "8" "9" "10" "11" 
[13] "12" "13" "14" "15" "16" "17" "18" "19" "20" "21" "22" "23" 
[25] "24" "25" "26" "27" "28" "29" "30" "31" "32" "33" "34" "35" 
[37] "36" "37" "38" "39" 

或（如https://stackoverflow.com/a/15665655/109618提到）：

sorted_labels <- order(levels(items$label)) - 1 
# order by itself is a 1-based vector 
# using `- 1` gives a 0-based vector 

每更新的問題，這將更新數據幀：

items$label <- factor(items$label, levels = sorted_labels) 

Answer 2

如果所有的整數都是公關的ESENT，那麼你可以簡單地使用order：

order(levels(items$label)) - 1 # where the minus 1 is for starting from 0 

如果不是所有的整數都存在，那麼你必須使用as.numeric，就像你擁有了它。