ColorPicker¶

Use lonboard with an ipywidgets ColorPicker object.

Example gif:

Dependencies¶

• lonboard

• geodatasets

  Run pip install geodatasets if needed.

Imports¶

In [1]:

import geodatasets
import geopandas as gpd
import ipywidgets

from lonboard import Map, SolidPolygonLayer

import geodatasets import geopandas as gpd import ipywidgets from lonboard import Map, SolidPolygonLayer

geodatasets.get_path will download the dataset if it hasn't been downloaded and cached before.

In [2]:

gdf = gpd.read_file(geodatasets.get_path("nybb"))

gdf = gpd.read_file(geodatasets.get_path("nybb"))

Create our basic map:

In [3]:

layer = SolidPolygonLayer.from_geopandas(gdf)
map_ = Map(layers=[layer])
map_

layer = SolidPolygonLayer.from_geopandas(gdf) map_ = Map(layers=[layer]) map_

/Users/kyle/github/developmentseed/lonboard/lonboard/_layer.py:99: UserWarning: GeoDataFrame being reprojected to EPSG:4326
  warnings.warn("GeoDataFrame being reprojected to EPSG:4326")

Out[3]:

Map(layers=[SolidPolygonLayer(table=pyarrow.Table
BoroCode: int64
BoroName: string
Shape_Leng: double
Shape_Ar…

Create the ColorPicker widget:

In [4]:

color_picker = ipywidgets.ColorPicker()
color_picker

color_picker = ipywidgets.ColorPicker() color_picker

Out[4]:

ColorPicker(value='black')

Note that the "data" contained by the color_picker instance is held by the value attribute:

In [5]:

color_picker.value

color_picker.value

Out[5]:

'black'

We'll now link the two widgets together, so that whenever the color picker is updated, ipywidgets will update the value of get_fill_color on the layer.

The format of dlink is:

• tuple: (source widget, attribute of source widget)
• tuple: (target widget, attribute of target widget)

So we use the below syntax to link color_picker.value to layer.get_fill_color.

We need to use dlink, not link, which creates a one-directional link (from the color picker to the layer) and not a bi-directional link. This is because the color picker and the layer have a different color representation under the hood (ColorPicker stores a hex string; the SolidPolygonLayer works in terms of RGBA color integers).

In [6]:

ipywidgets.dlink(
    (color_picker, 'value'),
    (layer, 'get_fill_color')
)

ipywidgets.dlink( (color_picker, 'value'), (layer, 'get_fill_color') )

Out[6]:

<traitlets.traitlets.directional_link at 0x168822610>

Now click on the color widget and change the color! You need to press Enter to select a specific color.

In [ ]: