Sharing state between callbacks solution

iris-solution.py

import dash
import dash_core_components as dcc
import dash_html_components as html
from dash.dependencies import Input, Output, State
import csv
import random
import json


def get_data():

    with open("iris.csv") as csvfile:
        reader = csv.reader(csvfile)
        csv_data = [r for r in reader]
        csv_data.pop(0)

    # clean data - convert numbers to types
    for i in range(len(csv_data)):
        row = csv_data[i]
        for j in range(len(row)):
            try:
                csv_data[i][j] = float(csv_data[i][j])
            except:
                pass

    return csv_data


def jitter_data(csv_data):
    for i in range(len(csv_data)):
        row = csv_data[i]
        for j in range(len(row)):
            if type(csv_data[i][j]) == float:
                csv_data[i][j] = csv_data[i][j] * random.random() * 2

    return csv_data


app = dash.Dash(__name__)

app.layout = html.Div(
    [
        html.Button(id="update-btn", children="update"),
        dcc.Graph(id="graph-1"),
        dcc.Graph(id="graph-2"),
        dcc.Graph(id="graph-3"),
        html.Div(id="intermediate-value", style={"display": "none"}),
    ]
)


def create_groups(data):
    groups = {}
    for i in range(len(data)):
        row = data[i]
        species = row[4]
        if species not in groups:
            groups[species] = {"x": [], "y": []}

        groups[species]["x"].append(row[0])
        groups[species]["y"].append(row[1])

    return groups


@app.callback(
    Output("intermediate-value", "children"), [Input("update-btn", "n_clicks")]
)
def update_btn(n_clicks):
    new_data = jitter_data(get_data())
    return json.dumps(new_data)


@app.callback(Output("graph-1", "figure"), [Input("intermediate-value", "children")])
def update_figure(str_data):
    group_name = "Setosa"

    new_data = json.loads(str_data)
    groups = create_groups(new_data)
    traces = []

    group = groups[group_name]
    traces.append(
        {
            "type": "scatter",
            "mode": "markers",
            "name": group_name,
            "x": group["x"],
            "y": group["y"],
        }
    )

    return {
        "data": traces,
        "layout": {
            "title": group_name,
            "xaxis": {"title": "Sepal.Length"},
            "yaxis": {"title": "Sepal.Width"},
        },
    }


@app.callback(Output("graph-2", "figure"), [Input("intermediate-value", "children")])
def update_figure(str_data):
    group_name = "Virginica"

    new_data = json.loads(str_data)
    groups = create_groups(new_data)
    traces = []

    group = groups[group_name]
    traces.append(
        {
            "type": "scatter",
            "mode": "markers",
            "name": group_name,
            "x": group["x"],
            "y": group["y"],
        }
    )

    return {
        "data": traces,
        "layout": {
            "title": group_name,
            "xaxis": {"title": "Sepal.Length"},
            "yaxis": {"title": "Sepal.Width"},
        },
    }


@app.callback(Output("graph-3", "figure"), [Input("intermediate-value", "children")])
def update_figure(str_data):
    group_name = "Versicolor"

    new_data = json.loads(str_data)
    groups = create_groups(new_data)
    traces = []

    group = groups[group_name]
    traces.append(
        {
            "type": "scatter",
            "mode": "markers",
            "name": group_name,
            "x": group["x"],
            "y": group["y"],
        }
    )

    return {
        "data": traces,
        "layout": {
            "title": group_name,
            "xaxis": {"title": "Sepal.Length"},
            "yaxis": {"title": "Sepal.Width"},
        },
    }


if __name__ == "__main__":
    app.run_server(debug=True)