How can I change the size of my Dash Graph?

问题

I'm running into layout difficulties with the plots on Dash. All the plots I generate with Dash seem to be auto sized to be very narrow, which makes it hard to actually view the data without some creative zooming.

As an example, when I view the source on one of my dashes, it looks like it computes the height of the main plot container (svg-container) to be 450px and the height of the graph itself to be 270px (looking at the subplots). It would be nice if I could make the graph, say, 700px.

My question is: what is the best way to adjust the dimensions of the graphs on Dash? My first guess would be to somehow attach a stylesheet, but I'm not sure how or what the appropriate css selectors would be.

Thank you!

回答1:

A Graph object contains a figure. Each figure has data and layout attributes.

You can set the height in the layout.

dcc.Graph(
    id="my-graph",
    figure={
        "data": [
            {"x": [1, 2, 3], "y": [4, 1, 2], "type": "bar"},
            {"x": [1, 2, 3], "y": [2, 4, 5], "type": "bar"},
        ],
        "layout": {
            "title": "My Dash Graph",
            "height": 700,  # px
        },
    },
)

According to the Plotly figure object schema, height must be a number greater than or equal to 10, and its default is 450 (px).

Keep in mind that you can create a Graph object and set figure later, in a dash callback.

For example, if the value of a dcc.Slider affects the figure attribute of your Graph you will have:

import plotly.graph_objs as go

dcc.Graph(id="my-graph")

@app.callback(
    output=Output("my-graph", "figure"),
    inputs=Input("slider", "value")])
def update_my_graph(value):
    data = go.Data(
        [
            go.Bar(x=[1, 2, 3], y=[4, 1, 2]),
            go.Bar(x=[1, 2, 3], y=[2, 4, 5]),
        ]
    layout = go.Layout(
        title="My Dash Graph",
        height=700
        )
    figure = go.Figure(data=data, layout=layout)
    return figure

回答2:

I did this by placing the plot's div as a sub-div inside a parent div, then setting the size of the parent div. Something like this:

# main parent div for the app
main_div = html.Div(children = [
    # sub-div for the plot
    html.Div(children = [
                dcc.Graph(id = 'my-plot'),
    ])
    ],
    # set the sizing of the parent div
    style = {'display': 'inline-block', 'width': '48%'})

As your app grows in complexity you will probably need to set up more div nesting for this to work. And you could also probably just set the style on the plot's sub-div directly, depending on how you've configured things.

Also, I might suggest following the official Dash forums here since there will probably be more users there, along with the Dash dev himself posting frequently: https://community.plot.ly/c/dash

来源：https://stackoverflow.com/questions/46287189/how-can-i-change-the-size-of-my-dash-graph

标签

python

plotly

plotly-dash