compute_align: Align positions using length.

Description

This compute function is often used in conjunction with compute_count, when used on data with a continuous x variable. By default, the computed width will be equal to the resolution of the data, or, in other words the smallest difference between two values in the data.

Usage

compute_align(x, var, length = NULL, align = 0.5, dir = "x")

Arguments

Dataset-like object to align. Built-in methods for data frames, grouped data frames and ggvis visualisations.

var

Name of variable to compute width of.

length

An absolute length to use. If NULL (the default), the width will be equivalent to the resolution of the data.

align

Where does the existing variable fall on the new bins? 0 = left edge, 0.5 = center, 1 = right edge.

dir

Direction, i.e. "x" or "y". Used to generate variable names in output.

Value

The original data frame, with additional columns:

'dir'min_

left boundary of bin

'dir'max_

right boundary of bin

'dir'len_

width of bin

Details

An absolute width for each x can be specified by using the width argument. If width is NULL (the default), it will use the resolution of the data as the width.

Examples

Run this code

# NOT RUN {
mtcars %>% compute_count(~disp) %>% compute_align(~x_)
mtcars %>% compute_count(~mpg) %>% compute_align(~x_)

# Use a specific width
pressure %>% compute_count(~temperature) %>% compute_align(~x_)
pressure %>% compute_count(~temperature) %>% compute_align(~x_, length = 5)

# It doesn't matter whether you transform inside or outside of a vis
mtcars %>% compute_count(~cyl, ~wt) %>%
  compute_align(~x_, length = .5) %>%
  ggvis(x = ~xmin_, x2 = ~xmax_, y = ~count_, y2 = 0) %>%
  layer_rects()

mtcars %>%
  ggvis(x = ~xmin_, x2 = ~xmax_, y = ~count_, y2 = 0) %>%
  compute_count(~cyl, ~wt) %>%
  compute_align(~x_) %>%
  layer_rects()

# Varying align
mtcars %>%
  ggvis(x = ~xmin_, x2 = ~xmax_, y = ~count_, y2 = 0) %>%
  compute_count(~cyl, ~wt) %>%
  compute_align(~x_, length = 0.5, align = input_slider(0, 1)) %>%
  layer_rects()
# }