日食

使用谷歌搜索兴趣数据绘制地图，跟踪日食在美国的路径。此示例演示了如何使用LinearColorMapper和颜色条。

细节

样本数据:

bokeh.sampledata.us_states

Bokeh API:

figure.patches，bokeh.models.ColumnDataSource，bokeh.models.LinearColorMapper，bokeh.models.ColorBar

更多信息:

颜色条

关键词:

颜色条，标签，地图，面片

from os.path import dirname, join, realpath

import pandas as pd
import shapefile as shp

from bokeh.models import ColumnDataSource, Label
from bokeh.plotting import figure, show
from bokeh.sampledata.us_states import data
from bokeh.transform import linear_cmap

ROOT = dirname(realpath(__file__))

states = pd.DataFrame.from_dict(data, orient="index")
states.drop(["AK", "HI"], inplace=True)

trends = pd.read_csv(join(ROOT, "eclipse_data/trends.csv"))

df = states.merge(trends, left_on="name", right_on="Region")

totality_path = shp.Reader(join(ROOT, "eclipse_data/upath17")).shapes()[0]

p = figure(
    width=1000, height=600, background_fill_color="#333344",
    tools="", toolbar_location=None, x_axis_location=None, y_axis_location=None,
)

p.grid.grid_line_color = None

p.title.text = "Google Search Trends and the Path of Solar Eclipse, 21 August 2017"
p.title.align = "center"
p.title.text_font_size = "21px"
p.title.text_color = "#333344"

source = ColumnDataSource(data=dict(
    state_xs=df.lons,
    state_ys=df.lats,
    trend=df["solar eclipse"],
))

us = p.patches(
    "state_xs", "state_ys", source=source,
    fill_color=linear_cmap("trend", palette="TolYlOrBr5", low=0, high=100),
    line_color="#333344", line_width=1,
)

p.x_range.renderers = p.y_range.renderers = [us]

totality_x, totality_y = zip(*totality_path.points)
p.patch(
    totality_x, totality_y,
    fill_color="black", fill_alpha=0.7, line_color=None,
)

p.add_layout(Label(
    text="Solar eclipse path of totality",
    x=-76.3, y=31.4, angle=-36.5, angle_units="deg",
    text_baseline="middle", text_font_size="11px", text_color="silver",
))

p.add_layout(us.construct_color_bar(
    title='Popularity of "solar eclipse" search term',
    location="bottom_left", orientation="horizontal",
    title_text_font_size="16px", title_text_font_style="bold",
    title_text_color="lightgrey", major_label_text_color="lightgrey",
    background_fill_alpha=0.0,
))

p.add_layout(Label(
    text="Source: Google Trends, NASA Scientific Visualization Studio",
    x=0, y=0, x_units="screen", y_units="screen", x_offset=40, y_offset=20,
    text_font_size="11px", text_color="gray", level="overlay",
))

show(p)