查找长格式日期之间的差异

Question

我有一个包含开始日期和结束日期的长格式数据集。对于每个 ID，您将看到多个开始和结束日期。我需要找出第一个结束日期和第二个开始日期之间的差异。我不确定如何使用两行来计算差异。感谢任何帮助。

df=data.frame(c(1,2,2,2,3,4,4),
              as.Date(c( "2010-10-01","2009-09-01","2014-01-01","2014-02-01","2009-01-01","2013-03-01","2014-03-01")),
              as.Date(c("2016-04-30","2013-12-31","2014-01-31","2016-04-30","2014-02-28","2013-05-01","2014-08-31"))); 
names(df)=c('id','start','end')

我的输出看起来像这样：

 df$diff=c(NA,1,1,NA,NA,304, NA)

Answer 1

这是我认为可以满足您要求的基础 R 尝试：

df$diff <- NA
split(df$diff, df$id) <- by(df, df$id, FUN=function(SD) c(SD$start[-1], NA) - SD$end)

df
#  id      start        end diff
#1  1 2010-10-01 2016-04-30   NA
#2  2 2009-09-01 2013-12-31    1
#3  2 2014-01-01 2014-01-31    1
#4  2 2014-02-01 2016-04-30   NA
#5  3 2009-01-01 2014-02-28   NA
#6  4 2013-03-01 2013-05-01  304
#7  4 2014-03-01 2014-08-31   NA

或者，在 data.table 中它将是：

setDT(df)[, diff := shift(start,n=1,type="lead") - end, by=id]

Answer 2

这是使用流行的 dplyr 包的替代方法：

library(dplyr)
df %>% 
  group_by(id) %>%
  mutate(diff = difftime(lead(start), end, units = "days"))
#      id      start        end     diff
#   (dbl)     (date)     (date)   (dfft)
# 1     1 2010-10-01 2016-04-30  NA days
# 2     2 2009-09-01 2013-12-31   1 days
# 3     2 2014-01-01 2014-01-31   1 days
# 4     2 2014-02-01 2016-04-30  NA days
# 5     3 2009-01-01 2014-02-28  NA days
# 6     4 2013-03-01 2013-05-01 304 days
# 7     4 2014-03-01 2014-08-31  NA days

如果需要，您可以将 diff 包裹在 as.numeric 中。

Answer 3

再次使用 base R，您可以执行以下操作：

df$noofdays <- as.numeric(as.difftime(df$end-df$start, units=c("days"), format="%Y-%m-%d"))

查找长格式日期之间的差异

Finding Difference Between Dates in Long format

r

datediff