monotonic {brolgar}

Are values monotonic? Always increasing, decreasing, or unvarying?

Description

These provides three families of functions to tell you if values are always increasing, decreasing, or unvarying, with the functions, increasing(), decreasing(), or unvarying(). Under the hood it uses diff to find differences, so if you like you can pass extra arguments to diff.

Usage

increasing(x, ...)

decreasing(x, ...)

unvarying(x, ...)

monotonic(x, ...)

Arguments

x

numeric or integer

...

extra arguments to pass to diff

Value

logical TRUE or FALSE

Examples

vec_inc <- c(1:10)
vec_dec<- c(10:1)
vec_ran <- c(sample(1:10))
vec_flat <- rep.int(1,10)

increasing(vec_inc)
increasing(vec_dec)
increasing(vec_ran)
increasing(vec_flat)

decreasing(vec_inc)
decreasing(vec_dec)
decreasing(vec_ran)
decreasing(vec_flat)

unvarying(vec_inc)
unvarying(vec_dec)
unvarying(vec_ran)
unvarying(vec_flat)

library(ggplot2)
library(gghighlight)
library(dplyr)

heights_mono <- heights %>%
  features(height_cm, feat_monotonic) %>%
  left_join(heights, by = "country")
  
  ggplot(heights_mono,
         aes(x = year,
             y = height_cm,
             group = country)) +
  geom_line() + 
  gghighlight(increase)

 ggplot(heights_mono,
        aes(x = year,
            y = height_cm,
             group = country)) +
  geom_line() + 
  gghighlight(decrease)

heights_mono %>%
filter(monotonic) %>%
  ggplot(aes(x = year,
             y = height_cm,
             group = country)) + 
  geom_line()
  
heights_mono %>%
  filter(increase) %>%
  ggplot(aes(x = year,
             y = height_cm,
             group = country)) + 
  geom_line()