R 中一个图中的多个折线图

Question

这是我在 R 中的数据框的示例：

structure(list(Series = c("A", "B", "A", "B", "A", "B", "A", 
"B", "A", "B", "A", "B", "A", "B", "A", "B", "A", "B", "A", "B"
), date = structure(c(19415, 19415, 19415, 19415, 19415, 19415,
19415, 19415, 19415, 19415, 19416, 19416, 19416, 19416, 19416,
19416, 19416, 19416, 19416, 19416), class = "Date"), ccy = c("CHF",
"CHF", "EUR", "EUR", "GBP", "GBP", "JPY", "JPY", "USD", "USD",
"CHF", "CHF", "EUR", "EUR", "GBP", "GBP", "JPY", "JPY", "USD",
"USD"), exp = c(-25.0260386883321, -13.4876728854438, 29.9242170197296,
28.1863060040971, -21.1816468152161, -17.6427844100702, -125.811601419233, 
-116.187338952966, -1574.53746806177, -944.410592575117, 13.687475030189,
5.55257290367663, 22.1373554559174, 9.839306286417, 9.60824459042358,
8.43043547492962, 75.9856738242059, 19.8785641759769, -2531.47779912341,
-313.689149325403)), row.names = c(NA, 20L), class = "data.frame")

对于

ccy

列中的每个唯一值，我想创建一个简单的折线图，其中包含两个系列（

series

列中的A和B）以及来自

date

和

exp

列的值。

每个图表的格式都是相同的，有两种不同颜色的线条和一个标题来标识它所指的

ccy

。输出将是方形折线图的网格。

解决这个问题的最佳方法是什么？