将箭头添加到ggplot中

Question

以下图表显示了不同情景下的排放水平。 如何在2030年的图表上添加双头箭头（或括号），以显示2030年的排放水平与2005年（黑色水平线）的排放水平之间的差异。

  ggplot() +
  geom_line(data=emissions.total, aes(x=year, y =Emissions, colour=Scenarios), linetype="dotted",show_guide = TRUE) +
  geom_line(data=emissions.total, aes(x=year, replace(Emissions, year>2016, NA), colour=Scenarios),show_guide = TRUE) +
  geom_hline(yintercept=emissions.total$Emissions[which(year==2005)], linetype="dashed", color = "black") +
  geom_text(data=emissions.total, aes(x=2002, y=173, label="2005 level"),size=4, color="black") 

Here is the dataset:

       emissions.total <- structure(list(year = c(2001, 2002, 2003, 2004, 2005, 2006, 2007, 
        2008, 2009, 2010, 2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 
        2019, 2020, 2021, 2022, 2023, 2024, 2025, 2026, 2027, 2028, 2029, 
        2030, 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 
        2011, 2012, 2013, 2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 
        2022, 2023, 2024, 2025, 2026, 2027, 2028, 2029, 2030, 2001, 2002, 
        2003, 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012, 2013, 
        2014, 2015, 2016, 2017, 2018, 2019, 2020, 2021, 2022, 2023, 2024, 
        2025, 2026, 2027, 2028, 2029, 2030), Scenarios = structure(c(1L, 
        1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
        1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 2L, 2L, 2L, 
        2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 
        2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 3L, 3L, 3L, 3L, 3L, 
        3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 
        3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L, 3L), .Label = c("BAU", "CFS1", 
        "CFS2"), class = "factor"), Emissions = c(153.26965, 154.976334, 
        159.694989, 165.146412, 167.66727, 165.675142, 172.29109, 170.972833, 
        167.471381, 174.56907, 174.22316, 175.402278, 178.575427, 175.016324, 
        173.921982, 171.566772, 183.196648982162, 185.7133178459, 188.287958106317, 
        190.9715983008, 193.682009668713, 196.746265921755, 200.036103617208, 
        203.568746857281, 207.355860289476, 211.410128322376, 215.739745848315, 
        220.349793165392, 225.242982999225, 230.422987110964, NA, NA, 
        NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 183.196648982162, 
        185.7133178459, 188.287958106317, 190.9715983008, 193.848647184694, 
        195.950925556132, 198.246162583056, 200.747913372455, 202.425883805268, 
        204.285914709484, 205.247579255324, 206.341337090443, 207.557093881178, 
        207.73139508312, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, NA, 
        NA, NA, NA, NA, NA, 183.196648982162, 185.7133178459, 188.287958106317, 
        190.9715983008, 193.848647184694, 186.069151568868, 178.759805219786, 
        171.895784395426, 165.448176205759, 159.390269465344, 153.693419034959, 
        148.328840591928, 143.268549966888, 138.48759672208)), row.names = c(NA, 
        -90L), class = c("tbl_df", "tbl", "data.frame"))

- Hossein

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geom_segment 支持 arrow= 参数。 - r2evans

Answer 1

试试这个：

y2005 <- na.omit(emissions.total$Emissions[ which(emissions.total$year == 2005) ])
y2030 <- na.omit(emissions.total$Emissions[ which(emissions.total$year == 2030) ])[1]

ggplot(emissions.total) +
  geom_line(aes(x=year, y =Emissions, colour=Scenarios), linetype="dotted",show_guide = TRUE) +
  geom_line(aes(x=year, replace(Emissions, year>2016, NA), colour=Scenarios),show_guide = TRUE) +
  geom_hline(yintercept=y2005, linetype="dashed", color = "black") +
  geom_text(aes(x=2002, y=173, label="2005 level"),size=4, color="black") +
  geom_segment(x = 2030, y = y2005, xend = 2030, yend = y2030,
               arrow = arrow(length = unit(0.03, "npc"), ends = "both"))

- r2evans