center_interval {padr}

Shift to the middle of each interval

Description

After thickening all the values are either shifted to the first or the last value of their interval. This function creates a vector from x, with the values shifted to the (approximate) center of the interval. This can give a more accurate picture of the aggregated data when plotting.

Usage

center_interval(x, shift = c("up", "down"), interval = NULL)

Arguments

x

A vector of class Date, POSIXct or POSIXlt.

shift

"up" or "down".

interval

The interval to be used for centering. If NULL, get_interval will be applied on x.

Details

The interval will be translated to number of days when x is of class Date, or number of seconds when x is of class POSIXt. For months and quarters this will be the average length of the interval. The translated units divided by two will be added by or subtracted from each value of x.

Value

Vector of the same class as x, with the values shifted to the (approximate) center.

Examples

library(dplyr)
library(ggplot2)
plot_set <- emergency %>%
  thicken("hour", "h") %>%
  count(h) %>%
  head(24)

ggplot(plot_set, aes(h, n)) + geom_col()

plot_set %>%
  mutate(h_center = center_interval(h)) %>%
  ggplot(aes(h_center, n)) + geom_col()