[英]Ranking within group and keep id in R data.table
I have a data.table with two grouping variables. 我有一个带有两个分组变量的data.table。 I want to calculate rankings with respect to group variable 1, while still keep the information of group. 我想计算有关组变量1的排名,同时仍保留组的信息。
# require(data.table)
# require(dplyr)
set.seed(1)
DT <- data.table(group = c(rep(1,5), rep(2, 5)),
id = c(letters[1:5], letters[1:5]),
var1 = rnorm(10),
var2 = runif(10))
# > DT
# group id var1 var2
# 1: 1 a -0.6264538 0.93470523
# 2: 1 b 0.1836433 0.21214252
# 3: 1 c -0.8356286 0.65167377
# 4: 1 d 1.5952808 0.12555510
# 5: 1 e 0.3295078 0.26722067
# 6: 2 a -0.8204684 0.38611409
# 7: 2 b 0.4874291 0.01339033
# 8: 2 c 0.7383247 0.38238796
# 9: 2 d 0.5757814 0.86969085
# 10: 2 e -0.3053884 0.34034900
I can calculate the rankings within group using 我可以使用以下方法计算组内的排名
DT[, lapply(.SD, function(x) percent_rank(x)),
.SDcols = c("var1", "var2"), by = .(group)]
# group var1 var2
# 1: 1 0.25 1.00
# 2: 1 0.50 0.25
# 3: 1 0.00 0.75
# 4: 1 1.00 0.00
# 5: 1 0.75 0.50
# 6: 2 0.00 0.75
# 7: 2 0.50 0.00
# 8: 2 1.00 0.50
# 9: 2 0.75 1.00
# 10: 2 0.25 0.25
I would also like to keep the id
column in the new table like 我也想将id
列保留在新表中,例如
# group id var1 var2
# 1: 1 A 0.25 1.00
# 2: 1 B 0.50 0.25
# 3: 1 C 0.00 0.75
# 4: 1 D 1.00 0.00
# 5: 1 E 0.75 0.50
# 6: 2 A 0.00 0.75
# 7: 2 B 0.50 0.00
# 8: 2 C 1.00 0.50
# 9: 2 D 0.75 1.00
# 10: 2 E 0.25 0.25
Using data.table 使用data.table
DT[,`:=`(var1 = percent_rank(var1),
var2 = percent_rank(var2))]
Using dplyr 使用dplyr
DT %>% mutate(var1 = percent_rank(var1),
var2 = percent_rank(var2))
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