如何最好地计算r的一年差异

Question

以下是示例代码。手头的任务是仅在第四季度创建一年差异（2021 Q4值-2020 Q4值）和百分比差异。所需的结果在下面。通常我会做一个pivot_wider等。但是，如何做到这一点，而不考虑所有季度？

  year <- c(2020,2020,2020,2020,2021,2021,2021,2021,2020,2020,2020,2020,2021,2021,2021,2021)
  qtr <- c(1,2,3,4,1,2,3,4,1,2,3,4,1,2,3,4)
  area <- c(1012,1012,1012,1012,1012,1012,1012,1012,1402,1402,1402,1402,1402,1402,1402,1402)
  employment <- c(100,102,104,106,108,110,114,111,52,54,56,59,61,66,65,49)

  test1 <- data.frame (year,qtr,area,employment)

  area       difference     percentage
  1012           5              4.7%
  1402           -10            -16.9

Answer 1

您将在季度使用过滤器：

test1 |>
  filter(qtr == 4) |>
  group_by(area) |>
    mutate(employment_lag = lag(employment),
           diff = employment - employment_lag) |>
    na.omit() |>
  ungroup() |>
  mutate(percentage = diff/employment_lag)

输出：

# A tibble: 2 × 7
   year   qtr  area employment  diff employment_start percentage
  <dbl> <dbl> <dbl>      <dbl> <dbl>            <dbl>      <dbl>
1  2021     4  1012        111     5              106     0.0472
2  2021     4  1402         49   -10               59    -0.169 

更新：添加正确的百分比。