plotnine.geoms.geom_map

class plotnine.geoms.geom_map(mapping=None, data=None, **kwargs)[source]

Draw map feature

The map feature are drawn without any special projections.

Usage

geom_map(mapping=None, data=None, stat='identity', position='identity',
         na_rm=False, inherit_aes=True, show_legend=None, raster=False,
         **kwargs)

Only the mapping and data can be positional, the rest must be keyword arguments. **kwargs can be aesthetics (or parameters) used by the stat.

Parameters
mappingaes, optional

Aesthetic mappings created with aes(). If specified and inherit.aes=True, it is combined with the default mapping for the plot. You must supply mapping if there is no plot mapping.

Aesthetic

Default value

geometry

alpha

1

color

'#111111'

fill

'#333333'

group

linetype

'solid'

shape

'o'

size

0.5

stroke

0.5

The bold aesthetics are required.

datadataframe, optional

The data to be displayed in this layer. If None, the data from from the ggplot() call is used. If specified, it overrides the data from the ggplot() call.

statstr or stat, optional (default: stat_identity)

The statistical transformation to use on the data for this layer. If it is a string, it must be the registered and known to Plotnine.

positionstr or position, optional (default: position_identity)

Position adjustment. If it is a string, it must be registered and known to Plotnine.

na_rmbool, optional (default: False)

If False, removes missing values with a warning. If True silently removes missing values.

inherit_aesbool, optional (default: True)

If False, overrides the default aesthetics.

show_legendbool or dict, optional (default: None)

Whether this layer should be included in the legends. None the default, includes any aesthetics that are mapped. If a bool, False never includes and True always includes. A dict can be used to exclude specific aesthetis of the layer from showing in the legend. e.g show_legend={'color': False}, any other aesthetic are included by default.

rasterbool, optional (default: False)

If True, draw onto this layer a raster (bitmap) object even ifthe final image is in vector format.

Notes

This geom is best suited for plotting a shapefile read into geopandas dataframe. The dataframe should have a geometry column.

Examples

[1]:
import pandas as pd
import geopandas as gp
from plotnine import *

%matplotlib inline

The Political Territories of Westeros

Layering different features on a Map

Read data and select features in Westeros only.

[2]:
continents = gp.read_file('data/lands-of-ice-and-fire/continents.shp')
islands = gp.read_file('data/lands-of-ice-and-fire/islands.shp')
lakes = gp.read_file('data/lands-of-ice-and-fire/lakes.shp')
rivers = gp.read_file('data/lands-of-ice-and-fire/rivers.shp')
political = gp.read_file('data/lands-of-ice-and-fire/political.shp')
wall = gp.read_file('data/lands-of-ice-and-fire/wall.shp')
roads = gp.read_file('data/lands-of-ice-and-fire/roads.shp')
locations = gp.read_file('data/lands-of-ice-and-fire/locations.shp')

westeros = continents.query('name=="Westeros"')
islands = islands.query('continent=="Westeros" and name!="Summer Islands"')
lakes = lakes.query('continent=="Westeros"')
rivers = rivers.query('continent=="Westeros"')
roads = roads.query('continent=="Westeros"')

wg = westeros.geometry[0]
bool_idx = [wg.contains(g) for g in locations.geometry]
westeros_locations = locations[bool_idx]
cities = westeros_locations[westeros_locations['type'] == 'City'].copy()

Create map by placing the features in layers in an order that limits obstraction.

The GeoDataFrame.geometry.centroid property has the center coordinates of polygons, we use these to place the labels of the political regions.

[3]:
# colors
water_color = '#a3ccff'
wall_color = 'white'
road_color = 'brown'

# Create label text by merging the territory name and
# the claimant to the territory
def fmt_labels(names, claimants):
    labels = []
    for name, claimant in zip(names, claimants):
        if name:
            labels.append('{} ({})'.format(name, claimant))
        else:
            labels.append('({})'.format(claimant))
    return labels


def calculate_center(df):
    """
    Calculate the centre of a geometry

    This method first converts to a planar crs, gets the centroid
    then converts back to the original crs. This gives a more
    accurate
    """
    original_crs = df.crs
    planar_crs = 'EPSG:3857'
    return df['geometry'].to_crs(planar_crs).centroid.to_crs(original_crs)


political['center'] = calculate_center(political)
cities['center'] = calculate_center(cities)

# Gallery Plot

(ggplot()
 + geom_map(westeros, fill=None)
 + geom_map(islands, fill=None)
 + geom_map(political, aes(fill='ClaimedBy'), color=None, show_legend=False)
 + geom_map(wall, color=wall_color, size=2)
 + geom_map(lakes, fill=water_color, color=None)
 + geom_map(rivers, aes(size='size'), color=water_color, show_legend=False)
 + geom_map(roads, aes(size='size'), color=road_color, alpha=0.5, show_legend=False)
 + geom_map(cities, size=1)
 + geom_text(
     political,
     aes('center.x', 'center.y', label='fmt_labels(name, ClaimedBy)'),
     size=8,
     fontweight='bold'
 )
 + geom_text(
     cities,
     aes('center.x', 'center.y', label='name'),
     size=8,
     ha='left',
     nudge_x=.20
 )
 + labs(title="The Political Territories of Westeros")
 + scale_fill_brewer(type='qual', palette=8)
 + scale_x_continuous(expand=(0, 0, 0, 1))
 + scale_y_continuous(expand=(0, 1, 0, 0))
 + scale_size_continuous(range=(0.4, 1))
 + coord_cartesian()
 + theme_void()
 + theme(figure_size=(8, 12), panel_background=element_rect(fill=water_color))
)
../_images/geom_ma_5_0.png
[3]:
<ggplot: (97654321012345679)>

Credit: cadaei of the cartographersguild website forum.