Init

.editorconfig

+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.py]
+max_line_length = 88
+indent_style = space
+indent_size = 4
+
+[*.{rst,ini,cfg}]
+indent_style = space
+indent_size = 4
+
+[*.{md,yml}]
+indent_style = space
+indent_size = 2

.gitignore

+.mypy_cache/

app.py

+from operator import itemgetter
+
+import dash
+import dash_core_components as dcc
+import dash_html_components as html
+from dash.dependencies import Input, Output
+
+
+def create_figure(town: str = None):
+    if town is None:
+        title = "All towns"
+        data = [
+            {
+                "x": town_data.get("x"),
+                "y": town_data.get("y"),
+                "type": "bar",
+                "name": town_data["title"],
+            }
+            for town_data in sorted(towns.values(), key=itemgetter("title"))
+        ]
+    else:
+        town_data = towns[town]
+        title = town_data["title"]
+        data = [
+            {
+                "x": town_data.get("x"),
+                "y": town_data.get("y"),
+                "type": "bar",
+                "name": title,
+            }
+        ]
+    return {
+        "data": data,
+        "layout": {"title": title},
+    }
+
+
+towns = {
+    "NYC": {"title": "New York City"},
+    "MTL": {"title": "Montréal", "x": [1, 2, 3], "y": [2, 4, 5]},
+    "SF": {"title": "San Francisco", "x": [1, 2, 3], "y": [4, 1, 2]},
+}
+initial_town = "MTL"
+
+app = dash.Dash(__name__)
+app.layout = html.Div(
+    children=[
+        html.H1(children="Hello Dash"),
+        html.Div(
+            children="""
+        Dash: A web application framework for Python.
+    """
+        ),
+        dcc.Dropdown(
+            id="town",
+            options=[
+                {"label": town_data["title"], "value": value}
+                for value, town_data in towns.items()
+            ],
+            value=initial_town,
+        ),
+        html.Div(id="label1"),
+        html.Div(
+            children=[
+                dcc.Graph(id="graph-selected", figure=create_figure(town=initial_town)),
+                dcc.Graph(id="graph-all", figure=create_figure()),
+            ],
+            style={"columnCount": 2},
+        ),
+    ]
+)
+
+
+@app.callback(
+    Output(component_id="graph-selected", component_property="figure"),
+    [Input(component_id="town", component_property="value")],
+)
+def update_trucmuche(input_value):
+    return create_figure(town=input_value)
+
+
+if __name__ == "__main__":
+    app.run_server(debug=True)

requirements-dev.txt

+black
+flake8
+isort
+mypy

requirements.in

+dash

requirements.txt

+#
+# This file is autogenerated by pip-compile
+# To update, run:
+#
+#    pip-compile
+#
+click==7.0                # via flask
+dash-core-components==1.6.0  # via dash
+dash-html-components==1.0.2  # via dash
+dash-table==4.5.1         # via dash
+dash==1.7.0
+dash_renderer==1.2.2      # via dash
+flask-compress==1.4.0     # via dash
+flask==1.1.1              # via dash, flask-compress
+future==0.18.2            # via dash
+itsdangerous==1.1.0       # via flask
+jinja2==2.10.3            # via flask
+markupsafe==1.1.1         # via jinja2
+plotly==4.4.1             # via dash
+retrying==1.3.3           # via plotly
+six==1.13.0               # via plotly, retrying
+werkzeug==0.16.0          # via flask

setup.cfg

+[flake8]
+# From https://pypi.org/project/flake8-black/
+# Recommend matching the black line length (default 88),
+# rather than using the flake8 default of 79:
+max-line-length = 88
+extend-ignore =
+    E203, # See https://github.com/PyCQA/pycodestyle/issues/373
+    D202, # See https://github.com/PyCQA/pydocstyle/pull/395
+enable-extensions=G # for flake8-logging-format
+
+[isort]
+# From https://black.readthedocs.io/en/stable/the_black_code_style.html#how-black-wraps-lines
+multi_line_output = 3
+include_trailing_comma = True
+force_grid_wrap = 0
+use_parentheses = True
+line_length = 88
+
+[pycodestyle]
+max_line_length = 88