查找具有相同值的所有行的总和。

Question

我有一个看起来像这样的数据框 -

>df
words num 
his    92   
his    91   
there  91   
you    90   
who    90   
come   89   
you    70   

现在，我想汇总常用字词并汇总其num列。所以我的最终输出就像 -

words   num
his     183   
there   91   
you     160   
who     90   
come    89   

我怎样才能在R中这样做？我知道这很简单，但无法弄清楚。

Answer 1

转换为data.table：

setDT(df)
df[, sum(num), by=words]
   words  V1
1:   his 183
2: there  91
3:   you 160
4:   who  90
5:  come  89