Problems plotting timeline with different dates in ggplot

Question

I am plotting data from two different years (07 and 08) on top of each other. These two years have slightly different dates, but when i plot it in R i am unable to get all the dates, R rearrange them to descending order, or splits them in two different years one after the other with a space between.

I need them on top of each other, with some of the dates slightly skewed.

The dates should be:

data_07[,1]<-c("7/6","21/6","31/6","14/7","28/7","11/8","25/8","8/9")

data_08[,1]<-c("7/6","21/6","5/7","19/7","2/8","16/8","25/8","8/9")

My script

data7 <- data.frame(
         Date = c("7/6","21/6","31/6","14/7","28/7","11/8","25/8","8/9"),
         variable = sample(c("Age 39-40", "Age 62-63"), 8, replace = TRUE),
         value = sample(1:8)
    )


data8 <- data.frame(
         Date = c("7/6","21/6","5/7","19/7","2/8","16/8","25/8","8/9"),
         variable = sample(c("Age 39-40", "Age 62-63"), 8, replace = TRUE),
         value = sample(1:8)
    )


p1<-ggplot(data7, 
    aes(x=Date, y=value, group=variable)) + 
    geom_point(size=2, shape = 15) +
    geom_line(linetype=1) +

    geom_line(data=data8, aes(x=Date, y=value, group=variable),linetype=2) +
    geom_point(data=data8, size=2, shape = 1)


 p1 + facet_wrap( ~ variable, nrow = 5, ncol = 1, scales= "fixed") +
    labs(x="Dates", y="Catches per 20 traps", title="") +
    theme(panel.grid.minor.y = element_blank(),
    panel.grid.major.y = element_blank())

Any help and suggestions are appreciated. Thank you!

Daniel

Answer 1

If the year isn't important for the plot, I would recommend assigning a new column in the data indicating the year, convert all your date to a common year, and then plot them in groups.

library(dplyr)
library(ggplot2)
library(lubridate)

#* dates are initially stored in dd/mm format.
#* create a variable where year = 2007
#* turn all dates to dd/mm/2000
data_07 <- data.frame(date = c("7/6","21/6","31/6","14/7","28/7","11/8","25/8","8/9"),
                      y = rnorm(8),
                      stringsAsFactors=FALSE) %>%
  mutate(year = 2007,
         date = dmy(paste0(date,"/2000")))


data_08 <- data.frame(date = c("7/6","21/6","5/7","19/7","2/8","16/8","25/8","8/9"),
                      y = rnorm(8),
                      stringsAsFactors=FALSE) %>%
  mutate(year = 2008,
         date = dmy(paste0(date,"/2000")))

both_years <- bind_rows(data_07, data_08)

ggplot(data = both_years,
       mapping = aes(x = date,
                     y = y,
                     colour = factor(year))) + 
  geom_point() + 
  geom_line()