使用 apply 函数对排序后的数据集进行排名

Question

我的数据框如下所示:

head(temp$HName)

[1] "UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT TYLER"
[2] "METHODIST HOSPITAL,THE"                            
[3] "TOMBALL REGIONAL MEDICAL CENTER"                   
[4] "METHODIST SUGAR LAND HOSPITAL"                     
[5] "GULF COAST MEDICAL CENTER"                         
[6] "VHS HARLINGEN HOSPITAL COMPANY LLC"   

head(temp$Rate)

[1] 7.3 8.3 8.7 8.7 8.8 8.9
76 Levels: 7.3 8.3 8.7 8.8 8.9 9 9.1 9.2 9.3 9.4 9.5 9.6 ... 17.1

> head(temp$Rank)
[1] NA NA NA NA NA NA

temp$Rate 已排序。我正在尝试编写一个函数 assignRank ，它为我提供了一个新列 temp$Rank ，其值为 1, 2, 3, 3, 4, 5

我的代码如下:

tapply(temp$Rank,temp$Rate, assignRank)

哪里:

    assignRank<- function(r=1){
      temp$Rank <- r
      r <- r + 1
      return(r)
    }

运行tapply时出现以下错误

   tapply(temp$Rank,temp$Rate, assignRank)
 Show Traceback

 Rerun with Debug
 Error in `$<-.data.frame`(`*tmp*`, "Rank", value = c(NA, NA)) : 
  replacement has 2 rows, data has 301 

请告诉我哪里出错了？

Answer 1

我使用 data.table 来做这样的事情，因为排序和排名都是非常高效/简单的语法

library(data.table)
setkey(setDT(temp), Rate) # This will sort your data set by Rate in case it's not yet sorted
temp[, Rank := .GRP, by = Rate]
temp
#                                                 HName Rate Rank
# 1: UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT TYLER  7.3    1
# 2:                             METHODIST HOSPITAL,THE  8.3    2
# 3:                    TOMBALL REGIONAL MEDICAL CENTER  8.7    3
# 4:                      METHODIST SUGAR LAND HOSPITAL  8.7    3
# 5:                          GULF COAST MEDICAL CENTER  8.8    4
# 6:                 VHS HARLINGEN HOSPITAL COMPANY LLC  8.9    5

或者您可以使用基本 R 轻松执行相同操作(假设您的数据按排名排序)，只需执行

as.numeric(factor(temp$Rate))
## [1] 1 2 3 3 4 5

或者也可以使用 dplyr 包中的 dense_rank 函数(这不需要需要对数据集进行排序)

library(dplyr)
temp %>% 
  mutate(Rank = dense_rank(Rate))
#                                                HName Rate Rank
# 1 UNIVERSITY OF TEXAS HEALTH SCIENCE CENTER AT TYLER  7.3    1
# 2                             METHODIST HOSPITAL,THE  8.3    2
# 3                    TOMBALL REGIONAL MEDICAL CENTER  8.7    3
# 4                      METHODIST SUGAR LAND HOSPITAL  8.7    3
# 5                          GULF COAST MEDICAL CENTER  8.8    4
# 6                 VHS HARLINGEN HOSPITAL COMPANY LLC  8.9    5