In plot_timeline(), order legend to match lines (#158)

* Order legend to match lines

On master, the order of the legend does not match the order of the
plot lines: https://i.imgur.com/baQlmlW.png

Now they do: https://i.imgur.com/F8CauVj.png

* Refactor to simplify body

DESCRIPTION

@@ -18,6 +18,7 @@ Depends:
     R (>= 3.4)
 Imports: 
     dplyr,
+    forcats,
     ggplot2,
     ggpubr,
     glue,

R/plot_timeline.R

@@ -47,39 +47,24 @@
 #'   labs(title = "Emission intensity trend for Cement")
 plot_timeline <- function(data, specs = timeline_specs(data)) {
   check_specs(specs, data)
+  data <- left_join(data, specs, by = "line_name")
 
-  measured <- filter(data, !.data$extrapolated)
-  plot <- ggplot() +
-    timeline_line(measured, specs) +
+  ggplot() +
+    geom_line(
+      data = data, aes(
+        x = .data$year,
+        y = .data$value,
+        colour = forcats::fct_reorder2(.data$label, .data$year, .data$value),
+        linetype = .data$extrapolated
+      )) +
+    expand_limits(y = 0) +
     scale_x_date(expand = expansion(mult = c(0, 0.1))) +
     scale_y_continuous(expand = expansion(mult = c(0, 0.1))) +
-    expand_limits(y = 0) +
-    scale_colour_manual(
-      values = specs$colour_hex,
-      labels = specs$label
-    )
-
-  if (any(data$extrapolated)) {
-    extrapolated <- filter(data, .data$extrapolated)
-    plot <- plot +
-      timeline_line(extrapolated, specs, linetype = .data$extrapolated) +
-      scale_linetype_manual(values = "dashed") +
-      guides(linetype = FALSE)
-  }
-
-  plot + theme_2dii()
-}
-
-timeline_line <- function(data, specs, ...) {
-  geom_line(
-    data = data,
-    aes(
-      x = .data$year,
-      y = .data$value,
-      colour = factor(.data$line_name, levels = specs$line_name),
-      ...
-    )
-  )
+    scale_colour_manual(values = unique(data$colour_hex)) +
+    scale_linetype_manual(
+      values = if (any(data$extrapolated)) c("solid", "dashed") else "solid") +
+    guides(linetype = FALSE) +
+    theme_2dii()
 }
 
 check_specs <- function(specs, data) {

tests/testthat/_snaps/plot_timeline.md

@@ -10,7 +10,7 @@
       
       $layers
       $layers[[1]]
-      mapping: x = ~.data$year, y = ~.data$value, colour = ~factor(.data$line_name, levels = specs$line_name) 
+      mapping: x = ~.data$year, y = ~.data$value, colour = ~forcats::fct_reorder2(.data$label, .data$year, .data$value), linetype = ~.data$extrapolated 
       geom_line: na.rm = FALSE, orientation = NA
       stat_identity: na.rm = FALSE
       position_identity 
@@ -21,12 +21,6 @@
       stat_identity: na.rm = FALSE
       position_identity 
       
-      $layers[[3]]
-      mapping: x = ~.data$year, y = ~.data$value, colour = ~factor(.data$line_name, levels = specs$line_name), linetype = ~.data$extrapolated 
-      geom_line: na.rm = FALSE, orientation = NA
-      stat_identity: na.rm = FALSE
-      position_identity 
-      
       
       $scales
       <ggproto object: Class ScalesList, gg>
@@ -515,7 +509,7 @@
       [1] "value"
       
       $labels$colour
-      [1] "factor(line_name, levels = specs$line_name)"
+      [1] "forcats::fct_reorder2(label, year, value)"
       
       $labels$linetype
       [1] "extrapolated"