Problem while plotting in grouped date values in R

May 6, 2022

I was trying to plot the max values from a dataset with x-axis = Date and the y-axis = max_value grouped by Stations, like the picture I found on this link, but I would like to make 5 plots (from different Stations).

This is a sample of my df:

df2 <- data.frame (Station  = c(1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 10, 10, 10),
                    Date = c("1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018"),
                    MAX_NO2 = c(55,52,58,76,98,12,14,23,54,76,90,99,43,32,76),
                    MAX_O3 = c(13,45,87,72,54,88,102,63,64,53,87,123,15,76,34))

This is the code I have:

library(tidyverse)
library(lubridate)
# your data
df2 %>% 
# add date as date
  mutate(date = ymd(Date)) %>%
# plot them
  ggplot( aes(x = date, y = MAX_NO2 , color = Station==1, group = Station==1)) +
  geom_line() + geom_point() +   theme_test()

But this is what I am plotting (this is from all the dataframe, not the sample):

Where the blue dots are the max values from the Station Nº1.That’s the only thing I want to plot, not the other ones in the same plot. In plot 1 Station 1, in plot 2 Station 2, etc.

>Solution :

The data.frame you provided is different from the plot. But if you want to get different plots for every station at once.Not calling a different ggplot for every station, maybe the facet_wrap() function (or facet_grid()) is helpful:

library(tidyverse)
library(lubridate)

df2 <- data.frame (Station  = c(1, 1, 1, 2, 2, 2, 3, 3, 3, 4, 4, 4, 10, 10, 10),
                   Date = c("1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018","1/1/2018",  "2/1/2018", "3/1/2018"),
                   MAX_NO2 = c(55,52,58,76,98,12,14,23,54,76,90,99,43,32,76),
                   MAX_O3 = c(13,45,87,72,54,88,102,63,64,53,87,123,15,76,34))

df2 %>% 
 mutate(Station = as.character(Station)) %>% 
 ggplot(aes(x = Date, y = MAX_NO2, colour=Station, group=Station)) +
 geom_line() + geom_point() +   theme_test() +
 facet_wrap(~Station)