can't find a solution for color the month in line graph in r-CodePudding

I would like to create a line graph with the following colors

yellow for january, february and march

red for april, may and june

green for july, august and september

blue for october, november and december

I have the following code:

temperature <- data.frame(
  stringsAsFactors = FALSE,
  Year= c(1998,1998,1998,1998,1998,1998,1998,1998,1998,1998,1998,1998,1999,1999,1999,1999,1999,1999,1999,1999,1999,1999,1999,1999,2000,2000,2000,2000,2000,2000,2000,2000,2000,2000,2000,2000,2001,2001,2001,2001,2001,2001,2001,2001,2001,2001,2001,2001,2002,2002,2002,2002,2002,2002,2002,2002,2002,2002,2002,2002),
  Month = c(1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4,5,6,7,8,9,10,11,12,1,2,3,4,5,6,7,8,9,10,11,12),
  Temperature = c(5,6,7,12,15,16,27,28,22,10,11,6,6,6,7,13,16,15,25,26,24,12,11,4,5,6,7,12,15,17,28,30,22,10,11,7,7,7,7,12,18,17,25,24,20,3,3,4,5,6,7,12,15,16,27,28,22,10,11,6),
  check.names = FALSE
)

temperature$date = as.Date(paste(temperature$Year, temperature$Month,1), format = "%Y %m %d")

ggplot(temperature,
       aes(
         x = date,
         y = Temperature
        ))  
  geom_line()  
  ggtitle("Time series")  
scale_x_date(date_breaks = "year", date_labels = "%Y", date_minor_breaks = "month")  
  xlab("Year")  
  ylab("Temperature")

But I don't know how to color the month and create a legend next to the line graph. Could someone please help?

The line is subdivided in different colors based on months

CodePudding user response：

Alternatively, to allow control of the colours with standard scale_colour_xxxx calls, you can override the default grouping defined by colour=Month with group=1. This will allow use of a legend.

ggplot(temperature,
       aes(
         x = date,
         y = Temperature,
         colour=as.factor(Month),
         group=1
       ))  
  geom_line()  
  ggtitle("Time series")  
  scale_x_date(
    date_breaks = "year", 
    date_labels = "%Y", 
    date_minor_breaks = "month"
  )  
  xlab("Year")  
  ylab("Temperature")

For a continuous "flow" of colours across Month, use colour=Month.

CodePudding user response：

I'm not sure how elegant (especially the part regarding ggplot) my approach is, but I used seas::mkseas() in the past to determine the season given in datetime objects. In combination with color initialization, one way to solve this might look like this:

library(ggplot2)
library(seas)

temperature$season <- mkseas(temperature$date, width="JFM")

colors <- c("JFM" = "yellow",
            "AMJ" = "red",
            "JAS" = "green",
            "OND" = "blue")

ggplot(temperature,
       aes(
         x = date,
         y = Temperature
       ))  
  geom_line(col = colors[temperature$season])  
  ggtitle("Time series")  
  scale_x_date(date_breaks = "year", date_labels = "%Y", date_minor_breaks = "month")  
  xlab("Year")  
  ylab("Temperature")