向数据框添加排名列 [英] Adding a ranking column to a dataframe

问题描述

这似乎是一项非常常见的任务，但我在 google 或 SO 中找不到解决方案.我想根据order.scores"应用于dat"的顺序向dat1"添加一个名为rank"的列.我尝试使用 row.names()，但 rownames 基于 'dat'，而不是 'dat1'.我也试过 'dat$rank <-rank(dat1)'，但这会产生错误信息.

This seems like it must be a very common task, but I can't find a solution in google or SO. I want to add a column called 'rank' to 'dat1' based on the sequence that 'order.scores' applies to 'dat'. I tried using row.names(), but the rownames are based on 'dat', not 'dat1'. I also tried 'dat$rank <-rank(dat1)', but this produces an error message.

fname<-c("Joe", "Bob", "Bill", "Tom", "Sue","Sam","Jane","Ruby")
score<-c(500, 490, 500, 750, 550, 500, 210, 320)
dat<-data.frame(fname,score)
order.scores<-order(dat$score,dat$fname)
dat1<-dat[order.scores,]

推荐答案

您可以按如下方式计算排序:

You can compute a ranking from an ordering as follows:

dat$rank <- NA
dat$rank[order.scores] <- 1:nrow(dat)
dat
#   fname score rank
# 1   Joe   500    5
# 2   Bob   490    3
# 3  Bill   500    4
# 4   Tom   750    8
# 5   Sue   550    7
# 6   Sam   500    6
# 7  Jane   210    1
# 8  Ruby   320    2

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