基于R中字段的运行计数 [英] Running count based on field in R

问题描述

我有这种格式的数据集

User       
1 
2
3
2
3
1  
1      

现在，我想添加一列"count"，该计数对用户的出现进行计数.我想要以以下格式输出.

Now I want to add a column saying count which counts the occurrence of the user. I want output in the below format.

User    Count
1       1
2       1 
3       1
2       2
3       2
1       2
1       3

我的解决方案很少，但是所有这些解决方案都有些慢.

I have few solutions but all those solutions are somewhat slow.

R中的运行计数变量

我的data.frame现在有100,000行，不久之后可能会达到100万行.我需要一个也很快的解决方案.

My data.frame has 100,000 rows now and soon it may go up to 1 million. I need a solution which is also fast.

推荐答案

您可以从我的"splitstackshape"包中使用 getanID :

You can use getanID from my "splitstackshape" package:

library(splitstackshape)
getanID(mydf, "User")
##    User .id
## 1:    1   1
## 2:    2   1
## 3:    3   1
## 4:    2   2
## 5:    3   2
## 6:    1   2
## 7:    1   3

这本质上是一种使用"data.table"的方法，其外观类似于以下内容:

This is essentially an approach with "data.table" that looks something like the following:

as.data.table(mydf)[, count := seq(.N), by = "User"][]

这篇关于基于R中字段的运行计数的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！