R中因子上计数的总和

Question

FeatureName     Uuid     Count 

ClickHeadline   ABC1     17 
ChangeSetting   ABC1     3  
ClickHeadline   CBA2     5 
ChangeSetting   CBA2     7 
SomethingElse   CBA2     5

Uuid    ClickHeadline    ChangeSetting    SomethingElse
ABC1    17               3                0
CBA2    5                7                5

我觉得我应该能在聚合函数上做到这一点，但我不知道如何告诉它，看一个变量的计数和。我知道我有点不知所措，但有人能帮我解决这个问题吗？

Answer 1

有多种可能性

如果需要sum，还可以使用reshape2packagedcast函数

df <- read.table(header=T, text='
                 FeatureName     Uuid     Count 

ClickHeadline   ABC1     17 
ChangeSetting   ABC1     3  
ClickHeadline   CBA2     5 
ChangeSetting   CBA2     7 
SomethingElse   CBA2     5
                 ')

library(reshape2)
dcast(df, Uuid ~ FeatureName, value.var="Count", sum)

  Uuid ChangeSetting ClickHeadline SomethingElse
1 ABC1             3            17             0
2 CBA2             7             5             5

如果dataset仅限于所提供的作用域，则只需使用基本reshape函数

out <- reshape(df, idvar="Uuid", timevar="FeatureName", v.names="Count", direction="wide")
out[is.na(out)] = 0
out
  Uuid Count.ClickHeadline Count.ChangeSetting Count.SomethingElse
1 ABC1                  17                   3                   0
3 CBA2                   5                   7                   5

xtabs(Count ~ Uuid+FeatureName, df)
      FeatureName
Uuid   ChangeSetting ClickHeadline SomethingElse
  ABC1             3            17             0
  CBA2             7             5             5

library(tidyr)
spread(df, key=FeatureName, value=Count, fill=0)
  Uuid ChangeSetting ClickHeadline SomethingElse
1 ABC1             3            17             0
2 CBA2             7             5             5