我想为这两个图形（geom_line和geom_bar）添加一个图例，但是根据我的代码，我在屏幕上看不到任何图例。
我想制作一个图例，指示几何条和几何线。
下面是我的完整代码。

# PGE Data
Date = seq(as.Date("2021-08-27"), as.Date("2021-09-27"), by="days")
Usage = c(4.3, 5, 7, 3.8, 5.6, 2.6, 4.8, 3.2, 2.6, 5.1,
3.3, 3.9, 2.5, 7.1, 3, 2.2, 6.1, 3.2, 3.2, 3.9,
5.6, 3.4, 3.3, 3.3, 4.4, 5.3, 2.9, 7.1, 3.3, 2.5, 3.1, 4.5)
Weather = c(70, 71, 65, 63, 62, 63, 62, 61, 61, 62,
67, 66, 67, 64, 64, 64, 65, 65, 62, 61,
62, 63, 64, 65, 68, 72, 65, 63, 63, 62, 62, 65)

pge = data.frame(Date, Usage, Weather)
head(pge, n = 10)

odd_weather = pge[seq_len(nrow(pge)) %% 2 == 1, ]
purple_weather = odd_weather[c(1, 5, 6, 7, 8, 10, 12, 13, 14, 15, 16), ]
white_weather = odd_weather[c(2, 3, 4, 9, 11), ]

purple_weather
white_weather

ggplot(data = pge) +
  geom_bar(mapping = aes(x = Date, y = Usage),
           width = 0.8,
           colour = 'steelblue3',
           fill = 'steelblue3',
           stat = "identity",
           show.legend = TRUE) +
  geom_line(mapping = aes(x = Date, y = Weather/15),
            color = 'purple', size = 1.2,
            show.legend = TRUE) +geom_text(data = purple_weather,
            mapping = aes(x = Date, y = Weather/15, label = paste0(Weather,"°", sep = '')),
            nudge_y = 0.4,
            size = 2,
            color ='purple') +
  geom_text(data = white_weather,
            mapping = aes(x = Date, y = Weather/15, label = paste0(Weather,"°", sep = '')),
            nudge_y = 0.4,
            size = 2,
            color ='white') +
  labs(title = bold('<') ~ '  Aug 27, 2021 - Sep 27 2021  ' ~  bold('>')) +
  scale_x_date(
    name = " ", 
    labels = c('Fri\n27', 'Tue\n31', 'Sat\n4', 'Wed\n8', 'Sun\n12', 'Thu\n16', 'Mon\n20', 'Fri\n24'),
    breaks = seq.Date(as.Date("2021-08-27"), as.Date("2021-09-24"), by = "4 days")) +
  scale_y_continuous(
    name = " ",
    limits = c(0, 8),
    breaks = seq(0.0, 8.0, by = 2.0), 
    labels = c('0.0', '2.0', '4.0', '6.0', '8.0 kWh')) +
  annotate("segment", x = median(c(as.Date("2021-08-31"), as.Date("2021-09-01"))),
           xend = median(c(as.Date("2021-08-31"), as.Date("2021-09-01"))),
           y = 0, yend = 8.0, colour = 'gray88', size = 0.5) +
  annotate("rect",
           xmin = median(c(as.Date("2021-08-31"), as.Date("2021-09-01"))),
           xmax = median(as.Date("2021-09-02")),
           ymin = 7.6, ymax = 8.0, alpha = 0.5, colour = 'gray88', fill = 'white') +
  annotate("text",
           x = as.Date("2021-09-01"),
           y = 7.85,
           label = "Sep",
           size = 2.5,
           hjust = 0.2) +
  theme(plot.background = element_rect(fill = 'gray96'),
        panel.background = element_rect(fill = 'gray96'),
        panel.grid.major.x = element_blank(),
        panel.grid.minor.x = element_blank(),
        panel.grid.major.y = element_line(color = 'gray88',
                                          size = 0.3,
                                          linetype = 1),
        panel.grid.minor.y = element_blank(),
        axis.ticks = element_blank(),
        plot.title = element_text(size = 8, color = 'gray30', hjust = 0.5),
        axis.text.x = element_text(vjust = 5, size = 8),
        axis.text.y = element_text(hjust = 0, size = 8),
        legend.direction = "horizontal",
        legend.background = element_blank(),
        legend.box.background = element_rect(linewidth = 1),
        legend.title = element_blank(),
        legend.box = "horizontal",
        legend.position = "bottom")

我的代码的结果如下所示。

我想把我的图做成这样。