Coordinate Systems¶

Preparation¶

In [1]:

import pandas as pd

from lets_plot import *
from lets_plot.geo_data import *
LetsPlot.setup_html()

The geodata is provided by © OpenStreetMap contributors and is made available here under the Open Database License (ODbL).

In [2]:

mpg = pd.read_csv("https://raw.githubusercontent.com/JetBrains/lets-plot-docs/master/data/mpg.csv")
mpg.head()

Out[2]:

	Unnamed: 0	manufacturer	model	displ	year	cyl	trans	drv	cty	hwy	fl	class
0	1	audi	a4	1.8	1999	4	auto(l5)	f	18	29	p	compact
1	2	audi	a4	1.8	1999	4	manual(m5)	f	21	29	p	compact
2	3	audi	a4	2.0	2008	4	manual(m6)	f	20	31	p	compact
3	4	audi	a4	2.0	2008	4	auto(av)	f	21	30	p	compact
4	5	audi	a4	2.8	1999	6	auto(l5)	f	16	26	p	compact

In [3]:

states_gdf = geocode_states().scope("UK").get_boundaries(6)
states_gdf.head()

Out[3]:

	state	found name	geometry
0	Cymru / Wales	Cymru / Wales	MULTIPOLYGON (((-3.25195 51.38550, -3.27393 51...
1	Scotland	Scotland	MULTIPOLYGON (((-7.44873 56.95696, -7.44873 56...
2	England	England	MULTIPOLYGON (((-5.05371 50.14875, -5.07568 50...
3	Northern Ireland	Northern Ireland	MULTIPOLYGON (((-6.30615 54.09806, -6.32812 54...

Cartesian Coordinates¶

Typical use case: changing limits of axes.

In [4]:

p = ggplot(mpg, aes("cty", "hwy")) + geom_point()
p1 = p + ggtitle("Default")
p2 = p + coord_cartesian(xlim=[10, 30], ylim=[10, 40]) + ggtitle("With coord_cartesian()")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 500, 375)
bunch.add_plot(p2, 500, 0, 500, 375)
bunch.show()

Fixed Coordinates¶

Typical use case: stretching a plot along one of the axes.

In [5]:

p = ggplot(mpg, aes("cty", "hwy")) + geom_point()
p1 = p + ggtitle("Default")
p2 = p + coord_fixed(ratio=1) + ggtitle("With coord_fixed()")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 500, 375)
bunch.add_plot(p2, 500, 0, 300, 375)
bunch.show()

Fixing coordinates could be combined with changing limits as for coord_cartesian().

In [6]:

p = ggplot(mpg, aes("cty", "hwy")) + geom_point()
p1 = p + coord_fixed(ratio=1) + ggtitle("Stretching only")
p2 = p + coord_fixed(ratio=1, xlim=[10, 30], ylim=[10, 40]) + ggtitle("With changing limits")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 300, 375)
bunch.add_plot(p2, 300, 0, 300, 375)
bunch.show()

Flipping Coordinates¶

In [7]:

p = ggplot(mpg, aes(x="fl")) + geom_bar()
p1 = p + ggtitle("Default")
p2 = p + coord_flip() + ggtitle("With coord_flip()")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 500, 375)
bunch.add_plot(p2, 500, 0, 300, 375)
bunch.show()

Flipping could also be combined with changing limits.

In [8]:

p = ggplot(mpg, aes(x="fl")) + geom_bar()
p1 = p + coord_flip() + ggtitle("Flipping only")
p2 = p + coord_flip(ylim=[0, 300]) + ggtitle("With changing limits")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 300, 375)
bunch.add_plot(p2, 300, 0, 300, 375)
bunch.show()

Also you can add flipping as an option to other coordinate systems.

In [9]:

p = ggplot(mpg, aes(x="fl")) + geom_bar()
p1 = p + coord_flip() + ggtitle("Flipping through coord_flip()")
p2 = p + coord_cartesian(flip=True) + ggtitle("Flipping through 'flip=True'")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 300, 375)
bunch.add_plot(p2, 300, 0, 300, 375)
bunch.show()

Map Coordinates¶

Typical use case: geospatial data.

In [10]:

p = ggplot() + geom_polygon(aes(fill="state"), data=states_gdf)
p1 = p + ggtitle("Default")
p2 = p + coord_map() + ggtitle("With coord_map()")

bunch = GGBunch()
bunch.add_plot(p1, 0, 0, 500, 375)
bunch.add_plot(p2, 500, 0, 500, 375)
bunch.show()