geom_pointdensity#

geom_pointdensity(mapping=None, *, data=None, stat=None, position=None, show_legend=None, inherit_aes=None, manual_key=None, sampling=None, tooltips=None, method=None, kernel=None, adjust=None, bw=None, n=None, map=None, map_join=None, use_crs=None, color_by=None, fill_by=None, **other_args)#

Plots data points and colors each point by the local density of nearby points.

Parameters:
mappingFeatureSpec

Set of aesthetic mappings created by aes() function. Aesthetic mappings describe the way that variables in the data are mapped to plot “aesthetics”.

datadict or Pandas or Polars DataFrame

The data to be displayed in this layer. If None, the default, the data is inherited from the plot data as specified in the call to ggplot.

statstr, default=’pointdensity’

The statistical transformation to use on the data for this layer, as a string.

positionstr or FeatureSpec, default=’identity’

Position adjustment. Either a position adjustment name: ‘dodge’, ‘jitter’, ‘nudge’, ‘jitterdodge’, ‘fill’, ‘stack’ or ‘identity’, or the result of calling a position adjustment function (e.g., position_dodge() etc.).

show_legendbool, default=True

False - do not show legend for this layer.

inherit_aesbool, default=True

False - do not combine the layer aesthetic mappings with the plot shared mappings.

manual_keystr or layer_key

The key to show in the manual legend. Specify text for the legend label or advanced settings using the layer_key() function.

samplingFeatureSpec

Result of the call to the sampling_xxx() function. To prevent any sampling for this layer pass value “none” (string “none”).

tooltipslayer_tooltips

Result of the call to the layer_tooltips() function. Specify appearance, style and content. Set tooltips=’none’ to hide tooltips from the layer.

method{‘auto’, ‘neighbours’, ‘kde2d’}, default=’auto’

The method to compute the density estimate.

  • 'neighbours' – estimates density from the number of nearby points.

  • 'kde2d' – estimates density using a smoothed 2D kernel density.

  • 'auto' – automatically selects an estimation method based on data size.

kernelstr, default=’gaussian’

The kernel we use to calculate the density function. Choose among ‘gaussian’, ‘cosine’, ‘optcosine’, ‘rectangular’ (or ‘uniform’), ‘triangular’, ‘biweight’ (or ‘quartic’), ‘epanechikov’ (or ‘parabolic’). Only used when method='kde2d'.

bwstr or list of float

The method (or exact value) of bandwidth. Either a string (choose among ‘nrd0’ and ‘nrd’), or a float array of length 2. Only used when method='kde2d'.

adjustfloat

If method='neighbours', adjust the radius in which to count neighbours. If method='kde2d', adjust the value of bandwidth by multiplying it.

nlist of int

The number of sampled points for plotting the function (on x and y direction correspondingly). Only used when method='kde2d'.

mapGeoDataFrame or Geocoder

Data containing coordinates of points.

map_joinstr or list

Keys used to join map coordinates with data. First value in pair - column/columns in data. Second value in pair - column/columns in map.

use_crsstr, optional, default=”EPSG:4326” (aka WGS84)

EPSG code of the coordinate reference system (CRS) or the keyword “provided”. If an EPSG code is given, then all the coordinates in GeoDataFrame (see the map parameter) will be projected to this CRS. Specify “provided” to disable any further re-projection and to keep the GeoDataFrame’s original CRS.

color_by{‘fill’, ‘color’, ‘paint_a’, ‘paint_b’, ‘paint_c’}, default=’color’

Define the color aesthetic for the geometry.

fill_by{‘fill’, ‘color’, ‘paint_a’, ‘paint_b’, ‘paint_c’}, default=’fill’

Define the fill aesthetic for the geometry.

other_args

Other arguments passed on to the layer. These are often aesthetics settings used to set an aesthetic to a fixed value, like color=’red’, fill=’blue’, size=3 or shape=21. They may also be parameters to the paired geom/stat.

Returns:
LayerSpec

Geom object specification.

Notes

Computed variables:

  • ..density.. : density estimate (mapped by default).

  • ..count.. : density * number of points (corresponds to number of nearby points for 'neighbours' method).

  • ..scaled.. : density estimate, scaled to maximum of 1.

geom_pointdensity() understands the following aesthetics mappings:

  • x : x-axis value.

  • y : y-axis value.

  • alpha : transparency level of the point. Accept values between 0 and 1.

  • color (colour) : color of the geometry. For more info see Color and Fill.

  • fill : fill color. Is applied only to the points of shapes having inner area. For more info see Color and Fill.

  • shape : shape of the point, an integer from 0 to 25. For more info see Point Shapes.

  • angle : rotation angle of the point shape, in degrees.

  • size : size of the point.

  • stroke : width of the shape border. Applied only to the shapes having border.

  • weight : used by ‘pointdensity’ stat to compute weighted density.

The data and map parameters of GeoDataFrame type support shapes Point and MultiPoint.

The map parameter of Geocoder type implicitly invokes get_centroids() function.

The conventions for the values of map_join parameter are as follows:

  • Joining data and GeoDataFrame object

    Data has a column named ‘State_name’ and GeoDataFrame has a matching column named ‘state’:

    • map_join=[‘State_Name’, ‘state’]

    • map_join=[[‘State_Name’], [‘state’]]

  • Joining data and Geocoder object

    Data has a column named ‘State_name’. The matching key in Geocoder is always ‘state’ (providing it is a state-level geocoder) and can be omitted:

    • map_join=’State_Name’

    • map_join=[‘State_Name’]

  • Joining data by composite key

    Joining by composite key works like in examples above, but instead of using a string for a simple key you need to use an array of strings for a composite key. The names in the composite key must be in the same order as in the US street addresses convention: ‘city’, ‘county’, ‘state’, ‘country’. For example, the data has columns ‘State_name’ and ‘County_name’. Joining with a 2-keys county level Geocoder object (the Geocoder keys ‘county’ and ‘state’ are omitted in this case):

    • map_join=[‘County_name’, ‘State_Name’]

To hide axis tooltips, set ‘blank’ or the result of element_blank() to the axis_tooltip, axis_tooltip_x or axis_tooltip_y parameter of the theme().

Examples

1import numpy as np
2from lets_plot import *
3LetsPlot.setup_html()
4n = 1000
5np.random.seed(42)
6x = np.random.normal(size=n)
7y = np.random.normal(size=n)
8ggplot({'x': x, 'y': y}, aes('x', 'y')) + \
9    geom_pointdensity()


 1import numpy as np
 2from lets_plot import *
 3LetsPlot.setup_html()
 4n = 5_000
 5np.random.seed(42)
 6x = np.random.poisson(size=n) + np.random.normal(scale=.1, size=n)
 7y = np.random.normal(size=n)
 8gggrid([
 9    ggplot({'x': x, 'y': y}, aes('x', 'y')) + \
10        geom_pointdensity(aes(color='..count..'),
11                          method=method) + \
12        ggtitle("method='{0}'".format(method))
13    for method in ['neighbours', 'kde2d']
14])


 1import numpy as np
 2from lets_plot import *
 3LetsPlot.setup_html()
 4n = 1000
 5np.random.seed(42)
 6data = {'x': 10 * np.random.normal(size=n) - 100, \
 7        'y': 3 * np.random.normal(size=n) + 40}
 8ggplot(data, aes('x', 'y')) + \
 9    geom_livemap(zoom=4) + \
10    geom_pointdensity(aes(fill='..density..'),
11                      color='black', shape=21,
12                      show_legend=False) + \
13    scale_fill_viridis()
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