dplyrは、2番目の列に配列に

Question

age_member<- c(1975, 1980, 1979, 1985, 1993, 1998) 
people<- c("male", "female", "male", "female", "male", "children") 

dataset <- data.frame(age_member, people) 

私の結果をもとcreati：私は子供の私が欲しいもの（第2）

、（最初の）男性のような他の配列を保っておりませんdplyr : filter a sequence of rows (in one column)
に答えます年齢差の新しい列（mutate）

dataset %>% 
    filter(first(people)=="male", last(people) == "female", n()==2) 

期待される結果

age_member people ages_diff 
1975 male   5 
1980 female   NA 
1979 male   6 
1985 female   NA 

私が試したもの：

dataset2 <-dataset %>% 
    mutate(ifelse(first(people)=="male", last(people) == "female",n()==2), last(age)- first(age)) 

Answer 1

我々は、我々は出力を得ることができ、また、そのせずに、

library(dplyr) 
dataset %>% 
     group_by(ind = cumsum(people == "male")) %>% 
     filter(first(people)=="male", last(people) == "female", n()==2) %>% 
     mutate(ages_diff = c(diff(age_member), NA)) %>% 
     ungroup() %>% 
     select(-ind) 
# A tibble: 4 x 3 
# age_member people ages_diff 
#  <dbl> <fctr>  <dbl> 
#1  1975 male   5 
#2  1980 female  NA 
#3  1979 male   6 
#4  1985 female  NA