将部分累加和列添加到数据框

Question

我的df按产品ID prodID和日期Date排序。我需要添加一个列，显示每个prodID在df中的累计指数。例如：如果proID仅出现一次，则该行的索引将为1。如果另外prodID出现在3行中（在df中是连续的，对于df是排序的），那么索引应该在第一行中为1，非常prodID，然后是2，然后是3在以下行中。 基本上我需要我最初的df：

 initial.df <- structure(list(prodID = c("009hpOpzwl", "00An0zNeEQ", "00An0zNeEQ", "00An0zNeEQ", "00An0zNeEQ", "00DtU3Bk6O", "00DtU3Bk6O", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk"), Date = c("2012-06", "2014-09", "2014-09", "2014-09", "2014-09", "2001-11", "2001-11", "2002-11", "2002-12", "2003-01", "2003-02", "2003-03"), status = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 5L, 5L, 5L, 5L, 5L), .Label = c("rare", "occasional", "amateur", "connoisseur", "expert", "fool"), class = "factor"),     rating = c(2.5, 4.7, 4.7, 4.7, 4.7, 4.4, 4.4, 3.5, 3.83,     3.36, 3.53, 3.78), over = c(68, 49, 49, 49, 49, 22, 22, 29,     38.33, 43.3, 39.53, 30.58)), class = "data.frame", row.names = c(NA, -12L), .Names = c("prodID", "Date", "status", "rating", "over"))

变为

new.df <- structure(list(prodID = c("009hpOpzwl", "00An0zNeEQ", "00An0zNeEQ", "00An0zNeEQ", "00An0zNeEQ", "00DtU3Bk6O", "00DtU3Bk6O", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk", "00FyjrH1kk"), Date = c("2012-06", "2014-09", "2014-09", "2014-09", "2014-09", "2001-11", "2001-11", "2002-11", "2002-12", "2003-01", "2003-02", "2003-03"), status = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 5L, 5L, 5L, 5L, 5L), .Label = c("rare", "occasional", "amateur", "connoisseur", "expert", "fool"), class = "factor"),     rating = c(2.5, 4.7, 4.7, 4.7, 4.7, 4.4, 4.4, 3.5, 3.83,     3.36, 3.53, 3.78), over = c(68, 49, 49, 49, 49, 22, 22, 29,     38.33, 43.3, 39.53, 30.58), index = c(1, 1, 2, 3, 4, 1, 2,     1, 2, 3, 4, 5)), .Names = c("prodID", "Date", "status", "rating", "over", "index"), row.names = c(NA, -12L), class = "data.frame")

提前感谢您提出任何建议

Answer 1

如果保证按照您声明的方式对数据进行排序，您可以使用ave功能实现此目的：

initial.df$index <- ave(initial.df$prodID, initial.df$prodID, FUN=function(x) seq(along=x))

Answer 2

为了完整起见，使用data.table时这是非常简单的操作，并且既有效又简短的语法并且通过引用创建列，只需：

library(data.table)
setDT(initial.df)[, index := seq_len(.N), prodID]

Answer 3

如果这个问题没有被其他人复制，我们已经有了data.table答案，这里是dplyr版本：

library(dplyr)
df %>% group_by(prodID) %>% mutate(index = row_number())

Answer 4

怎么样？

do.call(rbind, lapply(split(initial.df, initial.df$prodID), function(x) cbind(x, 1:nrow(x))))