R Newb ggplot2 issue

Question

I can't seem to get the geom_smooth data to work.

Example data:

## A tibble: 12 x 4
     UID   Month     n   tot
   <dbl>   <chr> <int> <dbl>
 1  1001 2016-04     2    75
 2  1001 2016-05     7   500
 3  1001 2016-06     3  1673
 4  1001 2016-07     5   288
 5  1001 2016-08     2   123
 6  1001 2016-09     3   739
 7  1001 2016-10     4   241
 8  1001 2016-12     2   512
 9  1001 2017-01     5   350
10  1001 2017-02     1    48
11  1001 2017-03     2   125
12  1001 2017-04     2    NA

Plotting code:

ggplot(one, aes(Month, tot)) + geom_point() + geom_smooth()

Do you think it has something to do with the Character value in the Date field?

Answer 1

Sometimes with lines and smoothers you have to specify which points should actually be joined with the line, so you can add group = 1 to ensure everything is treated as part of the same group:

ggplot(one, aes(Month, tot)) + 
    geom_point() + 
    geom_smooth(aes(group=1))

Answer 2

Yes, it is the format of the Month column which prevents the smooth. The question is: how to convert that column to a date? Given that you have only year and month, but date requires a day.

Two options. You could use as.yearmon from the zoo package to convert to a yearmon object:

library(dplyr)
one %>% 
  mutate(date = zoo::as.yearmon(Month)) %>% 
  ggplot(aes(date, tot)) + geom_point() + geom_smooth()

Or you could assume that the date is the first day of every month, for conversion to a date:

library(dplyr)
one %>% 
  mutate(date = as.Date(paste(Month, "01", sep = "-"))) %>%
  ggplot(aes(date, tot)) + geom_point() + geom_smooth()