Using Dates in the ggplot axis

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Libraries needed

library(dplyr)
library(ggplot2)
library(scales)

Create sample data

df <- data.frame(date     =  seq(as.Date('2021-01-01')
                                 , as.Date('2021-12-31')
                                 , by = "day")
                 , patients = as.integer(runif(365
                                               ,min = 1000
                                               , max = 1200
                 ))
                
)
df

Histogram of the data

hist(df$patients)

A simple line chart

pl <- ggplot(data = df,aes(x= date, y = patients))
pl <- pl + geom_line()
pl

Second chart adding the geom_smooth

pl <- ggplot(data = df,aes(x= date, y = patients))
pl <- pl + geom_line()
pl <- pl + geom_smooth(se = FALSE, color = "red")
pl <- pl + theme_bw()
pl

## `geom_smooth()` using method = 'loess' and formula 'y ~ x'

Create the third chart

We have changed the date_breaks to ‘1 week’ and minor_breaks to ‘1 day’

pl <- ggplot(data = df,aes(x= date, y = patients))
pl <- pl + geom_line()
pl <- pl + geom_smooth(se = FALSE, color = "red")
pl <- pl + theme_bw()
pl <- pl + scale_x_date(name = "Dates"
                        ,  date_labels = "%d %b"
                        ,  date_breaks = "1 week"
                        , minor_breaks = "1 day"
                        ,  sec.axis =  dup_axis(name = "Week number"
                                                ,labels = scales::date_format('%W')))

pl <- pl + theme(axis.text.x = element_text(angle = 90,vjust = 0.5))
pl <- pl + labs(title = "Daily patients")
pl <- pl + labs(subtitle = "Blue line shows mean")
pl <- pl + labs(caption = "@techanswerts88")
pl <- pl + geom_hline(yintercept = mean(df$patients), color = "blue")
pl

## `geom_smooth()` using method = 'loess' and formula 'y ~ x'

Create the fourth chart

We have changed the date_breaks to ‘1 month’ and minor_breaks to ‘1 week’

Try experimenting with different numbers.

For example ‘1 month’, ‘3 months’ , ‘1 year’ , ‘6 weeks’ and so on. Try and see the results.

pl <- ggplot(data = df,aes(x= date, y = patients))
pl <- pl + geom_line()
pl <- pl + geom_smooth(se = FALSE, color = "red")
pl <- pl + theme_bw()
pl <- pl + scale_x_date(name = "Dates"
                        ,  date_labels = "%d %b"
                        ,  date_breaks = "1 month"
                        , minor_breaks = "1 week"
                        ,  sec.axis =  dup_axis(name = "Week number"
                                                ,labels = scales::date_format('%W')))

pl <- pl + theme(axis.text.x = element_text(angle = 90,vjust = 0.5))
pl <- pl + labs(title = "Daily patients")
pl <- pl + labs(subtitle = "Blue line shows mean")
pl <- pl + labs(caption = "@techanswerts88")
pl <- pl + geom_hline(yintercept = mean(df$patients), color = "blue")
pl

## `geom_smooth()` using method = 'loess' and formula 'y ~ x'