假设我有两列数据.第一个包含诸如"First","Second","Third"等类别.第二个包含代表我看到"First"的次数的数字.
例如:
Category Frequency
First 10
First 15
First 5
Second 2
Third 14
Third 20
Second 3
我想按类别对数据进行排序并对频率求和:
Category Frequency
First 30
Second 5
Third 34
我怎么会在R？