Creating a new variable based on prior history

问题

I have data where I need to create a variable based on prior history, for example

 created<- c(2009,2010,2010,2011, 2012, 2011)
 person <- c(A, A, A, A, B, B)
 location<- c('London','Geneva', 'London', 'New York', 'London', 'London')
 df <- data.frame (created, person, location)

I want to create a variable called 'existing' that takes into account the prior years and sees if he/she has lived in that place and gives a value of 0 if the place is old(and they lived there. Any suggestions?

 library(dplyr) 
 df %>% group_by(person) %>% mutate (existing=0)

  existing<- c(1, 1, 0, 1, 0,1)

回答1:

Another dplyr option could be:

df %>%
 group_by(person, location) %>%
 mutate(existing = +(1:n() == 1))

  created person location existing
    <dbl> <fct>  <fct>       <int>
1    2009 A      London          1
2    2010 A      Geneva          1
3    2010 A      London          0
4    2011 A      New York        1
5    2012 B      London          1
6    2011 B      London          0

If sorting is required:

df %>%
 group_by(person, location) %>%
 arrange(created, .by_group = TRUE) %>%
 mutate(existing = +(1:n() == 1))

回答2:

You can try,

with(df, ave(location, person, FUN = function(i)as.integer(!duplicated(i))))
#[1] "1" "1" "0" "1" "1" "0"

回答3:

Based on the updated information from OP, we need to first arrange the data by person and year (created) and then use duplicated.

library(dplyr)

df %>% 
   arrange(person, created) %>% 
   group_by(person) %>% 
   mutate(existing = +(!duplicated(location)))

#  created person location existing
#    <dbl> <fct>  <fct>       <int>
#1    2009 A      London          1
#2    2010 A      Geneva          1
#3    2010 A      London          0
#4    2011 A      New York        1
#5    2011 B      London          1
#6    2012 B      London          0

回答4:

another option using data.table:

setDT(df)[order(person, created), existing := c(1L, rep(0L, .N-1L)), .(person, location)]

output:

   created person location existing
1:    2009      A   London        1
2:    2010      A   Geneva        1
3:    2010      A   London        0
4:    2011      A New York        1
5:    2012      B   London        0
6:    2011      B   London        1

来源：https://stackoverflow.com/questions/59091030/creating-a-new-variable-based-on-prior-history