如何区分多个面板中的值

Question

假设数据为：

data <- structure(list(country = c("Poland", "Poland", "Poland", "Poland", 
                             "Poland", "Poland", "Portugal", "Portugal", "Portugal", "Portugal", 
                             "Portugal", "Portugal", "Spain", "Spain", "Spain", "Spain", "Spain", 
                             "Spain"), Code = c("POL", "POL", "POL", "POL", "POL", "POL", 
                                                "PRT", "PRT", "PRT", "PRT", "PRT", "PRT", "ESP", "ESP", "ESP", 
                                                "ESP", "ESP", "ESP"), year = c(1950, 1951, 1952, 1953, 1954, 
                                                                               1955, 1950, 1951, 1952, 1953, 1954, 1955, 1950, 1951, 1952, 1953, 
                                                                               1954, 1955), IV = c(3, 3, 3, 3, 3, 3, 1, 1, 1, 1, 1, 1, 
                                                                                                          1, 1, 1, 1, 1, 1)), row.names = c(1L, 2L, 3L, 4L, 5L, 6L, 7L, 
                                                                                                                                            8L, 9L, 10L, 11L, 12L, 13L, 14L, 15L, 16L, 17L, 18L), class = "data.frame")

如何区分每个面板（国家）内的 IV 值？换句话说，我想用 1950 年减去 1951 年的 IV 值； 1952-1951； 1953-1952； 1954-1953； 1955-1954。对于每个国家来说也是如此。在结果数据集中（我们将其命名为“newdata”），每年的 IV 值必须显示其与前一年的 IV 值的差异； 1950年应该只是空的。

大家有什么建议吗？希望我的问题不会令人困惑。

Answer 1

也许在

diff

中使用

ave

。

> transform(data, dif=ave(IV, Code, FUN=\(x) c(NA, diff(x))))
    country Code year IV dif
1    Poland  POL 1950  3  NA
2    Poland  POL 1951  3   0
3    Poland  POL 1952  1  -2
4    Poland  POL 1953  3   2
5    Poland  POL 1954  3   0
6    Poland  POL 1955  1  -2
7  Portugal  PRT 1950  1  NA
8  Portugal  PRT 1951  1   0
9  Portugal  PRT 1952  1   0
10 Portugal  PRT 1953  1   0
11 Portugal  PRT 1954  1   0
12 Portugal  PRT 1955  1   0
13    Spain  ESP 1950  1  NA
14    Spain  ESP 1951  1   0
15    Spain  ESP 1952  3   2
16    Spain  ESP 1953  1  -2
17    Spain  ESP 1954  3   2
18    Spain  ESP 1955  1  -2

---

数据：

set.seed(42)
data$IV <- sample(data$IV)