Position adjustments and coordinate systems

STAT1003 – Statistical Techniques

Dr. Emi Tanaka

Australian National University

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Table of contents

• Visualising amounts and proportions
• A barplot with geom_bar()
• Summary data
• A barplot with geom_col()
• Position adjustments in barplots
• Position adjustments
• Pie or donut charts with coord_polar()
• Coordinate systems
• Summary

Visualising amounts and proportions

• geom_bar()
• geom_col()
• geom_point()
• geom_tile()
• geom_density()

A barplot with geom_bar()

• Here the stat = "count" is computing the frequencies for each category for you.

• You can alternatively use stat_count() and change the geom.

Summary data

• Sometimes your input data may already contain pre-computed counts.
• What is the observational unit (row) for the datasets below?

A barplot with geom_col()

• In this case, you don’t need stat = "count" to do the counting for you and use geom_col() instead.
• This is essential a short hand for geom_bar(stat = "identity") where stat = "identity" means that you will take the value as supplied without any statistical transformation.

Position adjustments in barplots

Position adjustments

• position_dodge() for grouped barplots
• position_dodge2() for improved grouped barplots
• position_fill() for stacked percentage barplots
• position_identity() to use the raw positions
• position_jitter() to add random noise to points
• position_jitterdodge() for jittered and dodged points
• position_nudge() to shift the position by a fixed amount
• position_stack() for stacked barplots

Pie or donut charts with coord_polar()

• The default coordinate system is the Cartesian coordinate system.

• But you can change this to a polar coordinate system like below.

Coordinate systems

• coord_cartesian() for Cartesian coordinate systems (default)
• coord_equal() is essentially coord_fixed(ratio = 1)
• coord_fixed() to use a fixed aspect ratio
• coord_flip() to flip the x and y
• coord_map() to use projection based on mapproj
• coord_munch() to improve rendering of large datasets
• coord_polar() to use polar coordinates
• coord_quickmap() for quick map coordinate system
• coord_radial() for radial coordinates
• coord_sf() for spatial data frames
• coord_transform() to transform the coordinate after the statistical transformation

Summary

• position_dodge()
• position_dodge2()
• position_fill()
• position_identity()
• position_jitter()
• position_jitterdodge()
• position_nudge()
• position_stack()

• coord_cartesian()
• coord_equal()
• coord_fixed()
• coord_flip()
  
• coord_map()
  
• coord_munch()
• coord_polar()
• coord_quickmap()
• coord_radial()
• coord_sf()
• coord_transform()