根據 R 中另一列中的排序創建列

Question

我有一個 dataframe 這是一個更長的版本：

council_name <- c("Southwark", "Southwark", "Southwark", "Lambeth", "Lambeth", "Lambeth", "Yorkshire", "Yorkshire", "Yorkshire")
quarter <- c("2006 Q1", "2006 Q2", "2006 Q3", "2006 Q1", "2006 Q2", "2006 Q3","2006 Q1", "2006 Q2", "2006 Q3")
treat <- c(1, 0, 1, 0, 0, 1, 0, 0, 0)
df.desired <- as.data.frame(c(council_name, as.yearqtr(quarter), treat, df, first.treatment))

我想要的是當“治療”第一次為“council_name”的每個值時，值為“四分之一”的列。 如果對於特定的委員會名稱，“治療”從不為 1，則為“0”。

這會是這樣的：

library(zoo)
council_name <- c("Southwark", "Southwark", "Southwark", "Lambeth", "Lambeth", "Lambeth", "Yorkshire", "Yorkshire", "Yorkshire")
quarter <- c("2006 Q1", "2006 Q2", "2006 Q3", "2006 Q1", "2006 Q2", "2006 Q3","2006 Q1", "2006 Q2", "2006 Q3")
treat <- c(1, 0, 1, 0, 0, 1, 0, 0, 0)
first.treatment <- c("2006 Q1", "2006 Q3", 0)
df.desired <- as.data.frame <- c(council_name, as.yearqtr(quarter), treat, df, first.treatment)

我用 group_by 和排序嘗試了不同的東西，但我從來沒有完全得到我想要的東西。

我嘗試的一個例子是：

merged2%>%
  group_by(council_name, year_qtr)%>%
  arrange(year_qtr)%>%
  mutate(first.treatment = by(year_qtr, head, 1))

但得到：

Error: Problem with `mutate()` input `first.treatment`. x unique() applies only to vectors ℹ Input `first.treatment` is `by(year_qtr, head, 1)`. ℹ The error occured in group 1: council_name = "Adur", year_qtr = 2006 Q2.

非常感謝！

Answer 1

我確實對示例數據進行了一些調整，但我非常希望，這就是你的意思。 我不喜歡返回字符串或0的想法。 應該始終返回相同的數據類型。 這就是為什么我的 answern 返回quarter或NA的原因。 如果您堅持返回可以使用is.na輕松“修復”的0 。

council_name <- c("Southwark", "Southwark", "Southwark", "Lambeth", "Lambeth", "Lambeth", "Yorkshire", "Yorkshire", "Yorkshire")
quarter <- c("2006 Q1", "2006 Q2", "2006 Q3", "2006 Q1", "2006 Q2", "2006 Q3","2006 Q1", "2006 Q2", "2006 Q3")
treat <- c(1, 0, 1, 0, 0, 1, 0, 0, 0)
df <- data.frame(council_name, quarter, treat)

treat.one <- function(d){
  line <- which(d$treat == 1)[1]
  return(d$quarter[line])
}

by(df, council_name, treat.one)

這需要

  council_name quarter treat
1    Southwark 2006 Q1     1
2    Southwark 2006 Q2     0
3    Southwark 2006 Q3     1
4      Lambeth 2006 Q1     0
5      Lambeth 2006 Q2     0
6      Lambeth 2006 Q3     1
7    Yorkshire 2006 Q1     0
8    Yorkshire 2006 Q2     0
9    Yorkshire 2006 Q3     0

並返回

> by(df, council_name, treat.one)
council_name: Lambeth
[1] "2006 Q3"
----------------------------------------- 
council_name: Southwark
[1] "2006 Q1"
----------------------------------------- 
council_name: Yorkshire
[1] NA

Answer 2

使用group_by時， mutate調用將依次考慮所有組中的每個變量。

因此，您可以編寫如下內容：

tibble(council_name, year_qtr=as.yearqtr(quarter), treat) %>% 
  group_by(council_name) %>% 
  arrange(year_qtr) %>% 
  mutate(first_treatment = year_qtr[treat==1][1]) %>% 
  arrange(council_name, year_qtr)

或者

tibble(council_name, year_qtr=as.yearqtr(quarter), treat) %>% 
  group_by(council_name) %>% 
  arrange(year_qtr) %>% 
  summarise(first_treatment = year_qtr[treat==1][1])

對於每個組，這都要求提供treat==1的year_qtr列，並獲取結果向量的第一個值。 這就是為什么事先排序（ arrange ）很重要。