Density plot using population data for a specific year - r

Question

Is it possible to create a density plot using this population data? Age_group is a categorical variable. Does it have to be numeric to create a density plot?
library(tidyverse)
df <- structure(list(year = c(1971, 1971, 1971, 1971, 1971, 1971, 1971,
1971, 1971, 1971, 1971, 1971, 1971, 1971, 1971, 1971, 1971, 1971
), age_group = structure(2:19, .Label = c("All ages", "0 to 4 years",
"5 to 9 years", "10 to 14 years", "15 to 19 years", "20 to 24 years",
"25 to 29 years", "30 to 34 years", "35 to 39 years", "40 to 44 years",
"45 to 49 years", "50 to 54 years", "55 to 59 years", "60 to 64 years",
"65 to 69 years", "70 to 74 years", "75 to 79 years", "80 to 84 years",
"85 to 89 years", "90 to 94 years", "95 to 99 years", "100 years and over",
"Median age"), class = "factor"), population = c(1836149, 2267794,
2329323, 2164092, 1976914, 1643264, 1342744, 1286302, 1284154,
1252545, 1065664, 964984, 785693, 626521, 462065, 328583, 206174,
101117)), class = c("tbl_df", "tbl", "data.frame"), row.names = c(NA,
-18L))

Answer 1

You can convert the text to numeric ranges, e.g.:
library(tidyverse) # if not already loaded
df %>%
# These extract the 1st and 3rd "word" of age_group
# Uses stringr::word(), loaded as part of tidyverse
mutate(age_min = word(age_group, 1) %>% as.numeric,
age_max = word(age_group, 3) %>% as.numeric) %>%
head
# A tibble: 6 x 5
year age_group population age_min age_max
<dbl> <fct> <dbl> <dbl> <dbl>
1 1971 0 to 4 years 1836149 0 4
2 1971 5 to 9 years 2267794 5 9
3 1971 10 to 14 years 2329323 10 14
4 1971 15 to 19 years 2164092 15 19
5 1971 20 to 24 years 1976914 20 24
6 1971 25 to 29 years 1643264 25 29
From that, you could display in ggplot a bunch of ways:
... %>%
ggplot(aes(age_numeric, population)) +
geom_step()
... %>%
ggplot(aes(age_numeric, population)) +
geom_col()
... %>%
ggplot(aes(age_numeric, y = population)) +
geom_density(stat = "identity")