Getting Started

Setup

Agenda

  • Setup

  • Hello Shiny

  • The user interface

  • The server

  • Recap

Goals of Session 1

  1. Understand the mechanics of a Shiny app (what to do, not why you do it)

  2. Develop comfort with failure and debugging

  3. You know where to go for help

How this session works

  • This session is going to be exercise based
  • All of the exercises and slides are running live on the website
  • You can do them on the website or open the apps in the apps/problem-sets folder
  • If you need help, put a red sticker on your laptop; when you’re done, put up a green sticker

Testing your setup

  1. In a terminal, type shiny create my-app
  2. Open my-app/app.py
  3. Click the “Run app” button in the top right of VS Code (screenshot)
  4. If your local setup doesn’t work, switch to Posit Workbench and try again

Hello Shiny

Agenda

  • Setup

  • Hello Shiny

  • The user interface

  • The server

  • Recap

What’s a Shiny app?

#| standalone: true
#| components: [viewer]
#| layout: horizontal
#| viewerHeight: 700
from pathlib import Path

import pandas as pd
import seaborn as sns

import shiny.experimental as x
from shiny import App, Inputs, Outputs, Session, reactive, render, req, ui

sns.set_theme()

# https://raw.githubusercontent.com/jcheng5/simplepenguins.R/main/penguins.csv

df = pd.read_csv(Path(__file__).parent / "penguins.csv", na_values="NA")
numeric_cols = df.select_dtypes(include=["float64"]).columns.tolist()
species = df["Species"].unique().tolist()
species.sort()

app_ui = x.ui.page_sidebar(
    x.ui.sidebar(
        ui.input_selectize(
            "xvar", "X variable", numeric_cols, selected="Bill Length (mm)"
        ),
        ui.input_selectize(
            "yvar", "Y variable", numeric_cols, selected="Bill Depth (mm)"
        ),
        ui.input_checkbox_group(
            "species", "Filter by species", species, selected=species
        ),
        ui.hr(),
        ui.input_switch("by_species", "Show species", value=True),
        ui.input_switch("show_margins", "Show marginal plots", value=True),
    ),
    x.ui.output_plot("scatter"),
)


def server(input: Inputs, output: Outputs, session: Session):
    @reactive.Calc
    def filtered_df() -> pd.DataFrame:
        """Returns a Pandas data frame that includes only the desired rows"""

        # This calculation "req"uires that at least one species is selected
        req(len(input.species()) > 0)

        # Filter the rows so we only include the desired species
        return df[df["Species"].isin(input.species())]

    @output
    @render.plot
    def scatter():
        """Generates a plot for Shiny to display to the user"""

        # The plotting function to use depends on whether margins are desired
        plotfunc = sns.jointplot if input.show_margins() else sns.scatterplot

        plotfunc(
            data=filtered_df(),
            x=input.xvar(),
            y=input.yvar(),
            hue="Species" if input.by_species() else None,
            hue_order=species,
            legend=False,
        )


app = App(app_ui, server)

## file: penguins.csv
Species,Island,Bill Length (mm),Bill Depth (mm),Flipper Length (mm),Body Mass (g),Sex,Year
Adelie,Torgersen,39.1,18.7,181,3750,male,2007
Adelie,Torgersen,39.5,17.4,186,3800,female,2007
Adelie,Torgersen,40.3,18,195,3250,female,2007
Adelie,Torgersen,NA,NA,NA,NA,NA,2007
Adelie,Torgersen,36.7,19.3,193,3450,female,2007
Adelie,Torgersen,39.3,20.6,190,3650,male,2007
Adelie,Torgersen,38.9,17.8,181,3625,female,2007
Adelie,Torgersen,39.2,19.6,195,4675,male,2007
Adelie,Torgersen,34.1,18.1,193,3475,NA,2007
Adelie,Torgersen,42,20.2,190,4250,NA,2007
Adelie,Torgersen,37.8,17.1,186,3300,NA,2007
Adelie,Torgersen,37.8,17.3,180,3700,NA,2007
Adelie,Torgersen,41.1,17.6,182,3200,female,2007
Adelie,Torgersen,38.6,21.2,191,3800,male,2007
Adelie,Torgersen,34.6,21.1,198,4400,male,2007
Adelie,Torgersen,36.6,17.8,185,3700,female,2007
Adelie,Torgersen,38.7,19,195,3450,female,2007
Adelie,Torgersen,42.5,20.7,197,4500,male,2007
Adelie,Torgersen,34.4,18.4,184,3325,female,2007
Adelie,Torgersen,46,21.5,194,4200,male,2007
Adelie,Biscoe,37.8,18.3,174,3400,female,2007
Adelie,Biscoe,37.7,18.7,180,3600,male,2007
Adelie,Biscoe,35.9,19.2,189,3800,female,2007
Adelie,Biscoe,38.2,18.1,185,3950,male,2007
Adelie,Biscoe,38.8,17.2,180,3800,male,2007
Adelie,Biscoe,35.3,18.9,187,3800,female,2007
Adelie,Biscoe,40.6,18.6,183,3550,male,2007
Adelie,Biscoe,40.5,17.9,187,3200,female,2007
Adelie,Biscoe,37.9,18.6,172,3150,female,2007
Adelie,Biscoe,40.5,18.9,180,3950,male,2007
Adelie,Dream,39.5,16.7,178,3250,female,2007
Adelie,Dream,37.2,18.1,178,3900,male,2007
Adelie,Dream,39.5,17.8,188,3300,female,2007
Adelie,Dream,40.9,18.9,184,3900,male,2007
Adelie,Dream,36.4,17,195,3325,female,2007
Adelie,Dream,39.2,21.1,196,4150,male,2007
Adelie,Dream,38.8,20,190,3950,male,2007
Adelie,Dream,42.2,18.5,180,3550,female,2007
Adelie,Dream,37.6,19.3,181,3300,female,2007
Adelie,Dream,39.8,19.1,184,4650,male,2007
Adelie,Dream,36.5,18,182,3150,female,2007
Adelie,Dream,40.8,18.4,195,3900,male,2007
Adelie,Dream,36,18.5,186,3100,female,2007
Adelie,Dream,44.1,19.7,196,4400,male,2007
Adelie,Dream,37,16.9,185,3000,female,2007
Adelie,Dream,39.6,18.8,190,4600,male,2007
Adelie,Dream,41.1,19,182,3425,male,2007
Adelie,Dream,37.5,18.9,179,2975,NA,2007
Adelie,Dream,36,17.9,190,3450,female,2007
Adelie,Dream,42.3,21.2,191,4150,male,2007
Adelie,Biscoe,39.6,17.7,186,3500,female,2008
Adelie,Biscoe,40.1,18.9,188,4300,male,2008
Adelie,Biscoe,35,17.9,190,3450,female,2008
Adelie,Biscoe,42,19.5,200,4050,male,2008
Adelie,Biscoe,34.5,18.1,187,2900,female,2008
Adelie,Biscoe,41.4,18.6,191,3700,male,2008
Adelie,Biscoe,39,17.5,186,3550,female,2008
Adelie,Biscoe,40.6,18.8,193,3800,male,2008
Adelie,Biscoe,36.5,16.6,181,2850,female,2008
Adelie,Biscoe,37.6,19.1,194,3750,male,2008
Adelie,Biscoe,35.7,16.9,185,3150,female,2008
Adelie,Biscoe,41.3,21.1,195,4400,male,2008
Adelie,Biscoe,37.6,17,185,3600,female,2008
Adelie,Biscoe,41.1,18.2,192,4050,male,2008
Adelie,Biscoe,36.4,17.1,184,2850,female,2008
Adelie,Biscoe,41.6,18,192,3950,male,2008
Adelie,Biscoe,35.5,16.2,195,3350,female,2008
Adelie,Biscoe,41.1,19.1,188,4100,male,2008
Adelie,Torgersen,35.9,16.6,190,3050,female,2008
Adelie,Torgersen,41.8,19.4,198,4450,male,2008
Adelie,Torgersen,33.5,19,190,3600,female,2008
Adelie,Torgersen,39.7,18.4,190,3900,male,2008
Adelie,Torgersen,39.6,17.2,196,3550,female,2008
Adelie,Torgersen,45.8,18.9,197,4150,male,2008
Adelie,Torgersen,35.5,17.5,190,3700,female,2008
Adelie,Torgersen,42.8,18.5,195,4250,male,2008
Adelie,Torgersen,40.9,16.8,191,3700,female,2008
Adelie,Torgersen,37.2,19.4,184,3900,male,2008
Adelie,Torgersen,36.2,16.1,187,3550,female,2008
Adelie,Torgersen,42.1,19.1,195,4000,male,2008
Adelie,Torgersen,34.6,17.2,189,3200,female,2008
Adelie,Torgersen,42.9,17.6,196,4700,male,2008
Adelie,Torgersen,36.7,18.8,187,3800,female,2008
Adelie,Torgersen,35.1,19.4,193,4200,male,2008
Adelie,Dream,37.3,17.8,191,3350,female,2008
Adelie,Dream,41.3,20.3,194,3550,male,2008
Adelie,Dream,36.3,19.5,190,3800,male,2008
Adelie,Dream,36.9,18.6,189,3500,female,2008
Adelie,Dream,38.3,19.2,189,3950,male,2008
Adelie,Dream,38.9,18.8,190,3600,female,2008
Adelie,Dream,35.7,18,202,3550,female,2008
Adelie,Dream,41.1,18.1,205,4300,male,2008
Adelie,Dream,34,17.1,185,3400,female,2008
Adelie,Dream,39.6,18.1,186,4450,male,2008
Adelie,Dream,36.2,17.3,187,3300,female,2008
Adelie,Dream,40.8,18.9,208,4300,male,2008
Adelie,Dream,38.1,18.6,190,3700,female,2008
Adelie,Dream,40.3,18.5,196,4350,male,2008
Adelie,Dream,33.1,16.1,178,2900,female,2008
Adelie,Dream,43.2,18.5,192,4100,male,2008
Adelie,Biscoe,35,17.9,192,3725,female,2009
Adelie,Biscoe,41,20,203,4725,male,2009
Adelie,Biscoe,37.7,16,183,3075,female,2009
Adelie,Biscoe,37.8,20,190,4250,male,2009
Adelie,Biscoe,37.9,18.6,193,2925,female,2009
Adelie,Biscoe,39.7,18.9,184,3550,male,2009
Adelie,Biscoe,38.6,17.2,199,3750,female,2009
Adelie,Biscoe,38.2,20,190,3900,male,2009
Adelie,Biscoe,38.1,17,181,3175,female,2009
Adelie,Biscoe,43.2,19,197,4775,male,2009
Adelie,Biscoe,38.1,16.5,198,3825,female,2009
Adelie,Biscoe,45.6,20.3,191,4600,male,2009
Adelie,Biscoe,39.7,17.7,193,3200,female,2009
Adelie,Biscoe,42.2,19.5,197,4275,male,2009
Adelie,Biscoe,39.6,20.7,191,3900,female,2009
Adelie,Biscoe,42.7,18.3,196,4075,male,2009
Adelie,Torgersen,38.6,17,188,2900,female,2009
Adelie,Torgersen,37.3,20.5,199,3775,male,2009
Adelie,Torgersen,35.7,17,189,3350,female,2009
Adelie,Torgersen,41.1,18.6,189,3325,male,2009
Adelie,Torgersen,36.2,17.2,187,3150,female,2009
Adelie,Torgersen,37.7,19.8,198,3500,male,2009
Adelie,Torgersen,40.2,17,176,3450,female,2009
Adelie,Torgersen,41.4,18.5,202,3875,male,2009
Adelie,Torgersen,35.2,15.9,186,3050,female,2009
Adelie,Torgersen,40.6,19,199,4000,male,2009
Adelie,Torgersen,38.8,17.6,191,3275,female,2009
Adelie,Torgersen,41.5,18.3,195,4300,male,2009
Adelie,Torgersen,39,17.1,191,3050,female,2009
Adelie,Torgersen,44.1,18,210,4000,male,2009
Adelie,Torgersen,38.5,17.9,190,3325,female,2009
Adelie,Torgersen,43.1,19.2,197,3500,male,2009
Adelie,Dream,36.8,18.5,193,3500,female,2009
Adelie,Dream,37.5,18.5,199,4475,male,2009
Adelie,Dream,38.1,17.6,187,3425,female,2009
Adelie,Dream,41.1,17.5,190,3900,male,2009
Adelie,Dream,35.6,17.5,191,3175,female,2009
Adelie,Dream,40.2,20.1,200,3975,male,2009
Adelie,Dream,37,16.5,185,3400,female,2009
Adelie,Dream,39.7,17.9,193,4250,male,2009
Adelie,Dream,40.2,17.1,193,3400,female,2009
Adelie,Dream,40.6,17.2,187,3475,male,2009
Adelie,Dream,32.1,15.5,188,3050,female,2009
Adelie,Dream,40.7,17,190,3725,male,2009
Adelie,Dream,37.3,16.8,192,3000,female,2009
Adelie,Dream,39,18.7,185,3650,male,2009
Adelie,Dream,39.2,18.6,190,4250,male,2009
Adelie,Dream,36.6,18.4,184,3475,female,2009
Adelie,Dream,36,17.8,195,3450,female,2009
Adelie,Dream,37.8,18.1,193,3750,male,2009
Adelie,Dream,36,17.1,187,3700,female,2009
Adelie,Dream,41.5,18.5,201,4000,male,2009
Gentoo,Biscoe,46.1,13.2,211,4500,female,2007
Gentoo,Biscoe,50,16.3,230,5700,male,2007
Gentoo,Biscoe,48.7,14.1,210,4450,female,2007
Gentoo,Biscoe,50,15.2,218,5700,male,2007
Gentoo,Biscoe,47.6,14.5,215,5400,male,2007
Gentoo,Biscoe,46.5,13.5,210,4550,female,2007
Gentoo,Biscoe,45.4,14.6,211,4800,female,2007
Gentoo,Biscoe,46.7,15.3,219,5200,male,2007
Gentoo,Biscoe,43.3,13.4,209,4400,female,2007
Gentoo,Biscoe,46.8,15.4,215,5150,male,2007
Gentoo,Biscoe,40.9,13.7,214,4650,female,2007
Gentoo,Biscoe,49,16.1,216,5550,male,2007
Gentoo,Biscoe,45.5,13.7,214,4650,female,2007
Gentoo,Biscoe,48.4,14.6,213,5850,male,2007
Gentoo,Biscoe,45.8,14.6,210,4200,female,2007
Gentoo,Biscoe,49.3,15.7,217,5850,male,2007
Gentoo,Biscoe,42,13.5,210,4150,female,2007
Gentoo,Biscoe,49.2,15.2,221,6300,male,2007
Gentoo,Biscoe,46.2,14.5,209,4800,female,2007
Gentoo,Biscoe,48.7,15.1,222,5350,male,2007
Gentoo,Biscoe,50.2,14.3,218,5700,male,2007
Gentoo,Biscoe,45.1,14.5,215,5000,female,2007
Gentoo,Biscoe,46.5,14.5,213,4400,female,2007
Gentoo,Biscoe,46.3,15.8,215,5050,male,2007
Gentoo,Biscoe,42.9,13.1,215,5000,female,2007
Gentoo,Biscoe,46.1,15.1,215,5100,male,2007
Gentoo,Biscoe,44.5,14.3,216,4100,NA,2007
Gentoo,Biscoe,47.8,15,215,5650,male,2007
Gentoo,Biscoe,48.2,14.3,210,4600,female,2007
Gentoo,Biscoe,50,15.3,220,5550,male,2007
Gentoo,Biscoe,47.3,15.3,222,5250,male,2007
Gentoo,Biscoe,42.8,14.2,209,4700,female,2007
Gentoo,Biscoe,45.1,14.5,207,5050,female,2007
Gentoo,Biscoe,59.6,17,230,6050,male,2007
Gentoo,Biscoe,49.1,14.8,220,5150,female,2008
Gentoo,Biscoe,48.4,16.3,220,5400,male,2008
Gentoo,Biscoe,42.6,13.7,213,4950,female,2008
Gentoo,Biscoe,44.4,17.3,219,5250,male,2008
Gentoo,Biscoe,44,13.6,208,4350,female,2008
Gentoo,Biscoe,48.7,15.7,208,5350,male,2008
Gentoo,Biscoe,42.7,13.7,208,3950,female,2008
Gentoo,Biscoe,49.6,16,225,5700,male,2008
Gentoo,Biscoe,45.3,13.7,210,4300,female,2008
Gentoo,Biscoe,49.6,15,216,4750,male,2008
Gentoo,Biscoe,50.5,15.9,222,5550,male,2008
Gentoo,Biscoe,43.6,13.9,217,4900,female,2008
Gentoo,Biscoe,45.5,13.9,210,4200,female,2008
Gentoo,Biscoe,50.5,15.9,225,5400,male,2008
Gentoo,Biscoe,44.9,13.3,213,5100,female,2008
Gentoo,Biscoe,45.2,15.8,215,5300,male,2008
Gentoo,Biscoe,46.6,14.2,210,4850,female,2008
Gentoo,Biscoe,48.5,14.1,220,5300,male,2008
Gentoo,Biscoe,45.1,14.4,210,4400,female,2008
Gentoo,Biscoe,50.1,15,225,5000,male,2008
Gentoo,Biscoe,46.5,14.4,217,4900,female,2008
Gentoo,Biscoe,45,15.4,220,5050,male,2008
Gentoo,Biscoe,43.8,13.9,208,4300,female,2008
Gentoo,Biscoe,45.5,15,220,5000,male,2008
Gentoo,Biscoe,43.2,14.5,208,4450,female,2008
Gentoo,Biscoe,50.4,15.3,224,5550,male,2008
Gentoo,Biscoe,45.3,13.8,208,4200,female,2008
Gentoo,Biscoe,46.2,14.9,221,5300,male,2008
Gentoo,Biscoe,45.7,13.9,214,4400,female,2008
Gentoo,Biscoe,54.3,15.7,231,5650,male,2008
Gentoo,Biscoe,45.8,14.2,219,4700,female,2008
Gentoo,Biscoe,49.8,16.8,230,5700,male,2008
Gentoo,Biscoe,46.2,14.4,214,4650,NA,2008
Gentoo,Biscoe,49.5,16.2,229,5800,male,2008
Gentoo,Biscoe,43.5,14.2,220,4700,female,2008
Gentoo,Biscoe,50.7,15,223,5550,male,2008
Gentoo,Biscoe,47.7,15,216,4750,female,2008
Gentoo,Biscoe,46.4,15.6,221,5000,male,2008
Gentoo,Biscoe,48.2,15.6,221,5100,male,2008
Gentoo,Biscoe,46.5,14.8,217,5200,female,2008
Gentoo,Biscoe,46.4,15,216,4700,female,2008
Gentoo,Biscoe,48.6,16,230,5800,male,2008
Gentoo,Biscoe,47.5,14.2,209,4600,female,2008
Gentoo,Biscoe,51.1,16.3,220,6000,male,2008
Gentoo,Biscoe,45.2,13.8,215,4750,female,2008
Gentoo,Biscoe,45.2,16.4,223,5950,male,2008
Gentoo,Biscoe,49.1,14.5,212,4625,female,2009
Gentoo,Biscoe,52.5,15.6,221,5450,male,2009
Gentoo,Biscoe,47.4,14.6,212,4725,female,2009
Gentoo,Biscoe,50,15.9,224,5350,male,2009
Gentoo,Biscoe,44.9,13.8,212,4750,female,2009
Gentoo,Biscoe,50.8,17.3,228,5600,male,2009
Gentoo,Biscoe,43.4,14.4,218,4600,female,2009
Gentoo,Biscoe,51.3,14.2,218,5300,male,2009
Gentoo,Biscoe,47.5,14,212,4875,female,2009
Gentoo,Biscoe,52.1,17,230,5550,male,2009
Gentoo,Biscoe,47.5,15,218,4950,female,2009
Gentoo,Biscoe,52.2,17.1,228,5400,male,2009
Gentoo,Biscoe,45.5,14.5,212,4750,female,2009
Gentoo,Biscoe,49.5,16.1,224,5650,male,2009
Gentoo,Biscoe,44.5,14.7,214,4850,female,2009
Gentoo,Biscoe,50.8,15.7,226,5200,male,2009
Gentoo,Biscoe,49.4,15.8,216,4925,male,2009
Gentoo,Biscoe,46.9,14.6,222,4875,female,2009
Gentoo,Biscoe,48.4,14.4,203,4625,female,2009
Gentoo,Biscoe,51.1,16.5,225,5250,male,2009
Gentoo,Biscoe,48.5,15,219,4850,female,2009
Gentoo,Biscoe,55.9,17,228,5600,male,2009
Gentoo,Biscoe,47.2,15.5,215,4975,female,2009
Gentoo,Biscoe,49.1,15,228,5500,male,2009
Gentoo,Biscoe,47.3,13.8,216,4725,NA,2009
Gentoo,Biscoe,46.8,16.1,215,5500,male,2009
Gentoo,Biscoe,41.7,14.7,210,4700,female,2009
Gentoo,Biscoe,53.4,15.8,219,5500,male,2009
Gentoo,Biscoe,43.3,14,208,4575,female,2009
Gentoo,Biscoe,48.1,15.1,209,5500,male,2009
Gentoo,Biscoe,50.5,15.2,216,5000,female,2009
Gentoo,Biscoe,49.8,15.9,229,5950,male,2009
Gentoo,Biscoe,43.5,15.2,213,4650,female,2009
Gentoo,Biscoe,51.5,16.3,230,5500,male,2009
Gentoo,Biscoe,46.2,14.1,217,4375,female,2009
Gentoo,Biscoe,55.1,16,230,5850,male,2009
Gentoo,Biscoe,44.5,15.7,217,4875,NA,2009
Gentoo,Biscoe,48.8,16.2,222,6000,male,2009
Gentoo,Biscoe,47.2,13.7,214,4925,female,2009
Gentoo,Biscoe,NA,NA,NA,NA,NA,2009
Gentoo,Biscoe,46.8,14.3,215,4850,female,2009
Gentoo,Biscoe,50.4,15.7,222,5750,male,2009
Gentoo,Biscoe,45.2,14.8,212,5200,female,2009
Gentoo,Biscoe,49.9,16.1,213,5400,male,2009
Chinstrap,Dream,46.5,17.9,192,3500,female,2007
Chinstrap,Dream,50,19.5,196,3900,male,2007
Chinstrap,Dream,51.3,19.2,193,3650,male,2007
Chinstrap,Dream,45.4,18.7,188,3525,female,2007
Chinstrap,Dream,52.7,19.8,197,3725,male,2007
Chinstrap,Dream,45.2,17.8,198,3950,female,2007
Chinstrap,Dream,46.1,18.2,178,3250,female,2007
Chinstrap,Dream,51.3,18.2,197,3750,male,2007
Chinstrap,Dream,46,18.9,195,4150,female,2007
Chinstrap,Dream,51.3,19.9,198,3700,male,2007
Chinstrap,Dream,46.6,17.8,193,3800,female,2007
Chinstrap,Dream,51.7,20.3,194,3775,male,2007
Chinstrap,Dream,47,17.3,185,3700,female,2007
Chinstrap,Dream,52,18.1,201,4050,male,2007
Chinstrap,Dream,45.9,17.1,190,3575,female,2007
Chinstrap,Dream,50.5,19.6,201,4050,male,2007
Chinstrap,Dream,50.3,20,197,3300,male,2007
Chinstrap,Dream,58,17.8,181,3700,female,2007
Chinstrap,Dream,46.4,18.6,190,3450,female,2007
Chinstrap,Dream,49.2,18.2,195,4400,male,2007
Chinstrap,Dream,42.4,17.3,181,3600,female,2007
Chinstrap,Dream,48.5,17.5,191,3400,male,2007
Chinstrap,Dream,43.2,16.6,187,2900,female,2007
Chinstrap,Dream,50.6,19.4,193,3800,male,2007
Chinstrap,Dream,46.7,17.9,195,3300,female,2007
Chinstrap,Dream,52,19,197,4150,male,2007
Chinstrap,Dream,50.5,18.4,200,3400,female,2008
Chinstrap,Dream,49.5,19,200,3800,male,2008
Chinstrap,Dream,46.4,17.8,191,3700,female,2008
Chinstrap,Dream,52.8,20,205,4550,male,2008
Chinstrap,Dream,40.9,16.6,187,3200,female,2008
Chinstrap,Dream,54.2,20.8,201,4300,male,2008
Chinstrap,Dream,42.5,16.7,187,3350,female,2008
Chinstrap,Dream,51,18.8,203,4100,male,2008
Chinstrap,Dream,49.7,18.6,195,3600,male,2008
Chinstrap,Dream,47.5,16.8,199,3900,female,2008
Chinstrap,Dream,47.6,18.3,195,3850,female,2008
Chinstrap,Dream,52,20.7,210,4800,male,2008
Chinstrap,Dream,46.9,16.6,192,2700,female,2008
Chinstrap,Dream,53.5,19.9,205,4500,male,2008
Chinstrap,Dream,49,19.5,210,3950,male,2008
Chinstrap,Dream,46.2,17.5,187,3650,female,2008
Chinstrap,Dream,50.9,19.1,196,3550,male,2008
Chinstrap,Dream,45.5,17,196,3500,female,2008
Chinstrap,Dream,50.9,17.9,196,3675,female,2009
Chinstrap,Dream,50.8,18.5,201,4450,male,2009
Chinstrap,Dream,50.1,17.9,190,3400,female,2009
Chinstrap,Dream,49,19.6,212,4300,male,2009
Chinstrap,Dream,51.5,18.7,187,3250,male,2009
Chinstrap,Dream,49.8,17.3,198,3675,female,2009
Chinstrap,Dream,48.1,16.4,199,3325,female,2009
Chinstrap,Dream,51.4,19,201,3950,male,2009
Chinstrap,Dream,45.7,17.3,193,3600,female,2009
Chinstrap,Dream,50.7,19.7,203,4050,male,2009
Chinstrap,Dream,42.5,17.3,187,3350,female,2009
Chinstrap,Dream,52.2,18.8,197,3450,male,2009
Chinstrap,Dream,45.2,16.6,191,3250,female,2009
Chinstrap,Dream,49.3,19.9,203,4050,male,2009
Chinstrap,Dream,50.2,18.8,202,3800,male,2009
Chinstrap,Dream,45.6,19.4,194,3525,female,2009
Chinstrap,Dream,51.9,19.5,206,3950,male,2009
Chinstrap,Dream,46.8,16.5,189,3650,female,2009
Chinstrap,Dream,45.7,17,195,3650,female,2009
Chinstrap,Dream,55.8,19.8,207,4000,male,2009
Chinstrap,Dream,43.5,18.1,202,3400,female,2009
Chinstrap,Dream,49.6,18.2,193,3775,male,2009
Chinstrap,Dream,50.8,19,210,4100,male,2009
Chinstrap,Dream,50.2,18.7,198,3775,female,2009

## file: requirements.txt
shiny==0.5.1
shinyswatch==0.2.4
seaborn==0.12.2
matplotlib==3.7.1

Key features of Shiny

  • Easy to develop
  • Extensible
  • Efficient

Why Shiny for Python?

  • Shiny is designed to take you from prototype to production
  • Easy enough to use for prototypes
  • Efficient enough to handle complexity
  • Everything you need to build production quality apps
  • You don’t need to throw away your Shiny apps

Anatomy of a Shiny App

To make a Shiny app work you need to do three things:

  1. Add inputs and outputs to the UI
  2. Create a rendering function
  3. Refer to inputs

Inputs and outputs

from shiny import Inputs, Outputs, Session, App, render, ui

app_ui = ui.page_fluid(
    ui.input_slider("n", "N", 0, 100, 20),
    ui.output_text_verbatim("txt"),
)


def server(input, output, session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"


app = App(app_ui, server)

Rendering function

from shiny import Inputs, Outputs, Session, App, render, ui

app_ui = ui.page_fluid(
    ui.input_slider("n", "N", 0, 100, 20),
    ui.output_text_verbatim("txt"),
)


def server(input, output, session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"


app = App(app_ui, server)

Refer to inputs

from shiny import Inputs, Outputs, Session, App, render, ui

app_ui = ui.page_fluid(
    ui.input_slider("n", "N", 0, 100, 20),
    ui.output_text_verbatim("txt"),
)


def server(input, output, session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"


app = App(app_ui, server)

The user interface

Agenda

  • Setup

  • Hello Shiny

  • The user interface

  • The server

  • Recap

UI functions

  • UI functions are in the ui submodule
  • Inputs start with ui.input_*() and take an id, and options
  • Outputs start with ui.output_*() and usually just take an id
  • Other functions like ui.h1() or ui.p() add static HTML to the app
  • We’ll get to layout functions in Session 3

Your turn

Go to exercises/1-hello-world or run apps/problem-sets/1-getting-started/1.0-hello-world locally.

The server

Agenda

  • Setup

  • Hello Shiny

  • The user interface

  • The server

  • Recap

Server function

  • Every Shiny app needs a server function
  • The server function executes for each user session
  • This function contains rendering functions which define how to turn inputs into outputs

Rendering functions

def server(input, output, session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"
  • Functions are defined inside the main server function
  • They need to be decorated with @output and @render.* in that order
  • The function name should match the output id
  • The return value is sent to the Shiny UI

Decorators are just functions

    @output
    @render.plot(alt="A body mass plot of penguins")
    def mass_plot():
        df = sample_data(penguins.copy(), input.sample())
        df = df.loc[df["body_mass"] < input.mass()]
        return dist_plot(df)
  • Decorators are functions which take other functions
  • Shiny uses them to identify reactive functions
  • They can take arguments

Simple app example

from shiny import Inputs, Outputs, Session, App, render, ui

app_ui = ui.page_fluid(
    ui.input_slider("n", "N", 0, 100, 20),
    ui.output_text_verbatim("txt"),
)


def server(input, output, session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"


app = App(app_ui, server)

Common problems

  • An output doesn’t render
  • An output doesn’t update when an input changes
  • There’s some weird error

Your turn

Go to exercises/2-debug or work through exercises 1.1-1.5 locally.

Connecting inputs to outputs

def server(input: Inputs, output: Outputs, session: Session):
    @output
    @render.text
    def txt():
        return f"n*2 is {input.n() * 2}"
  • Inputs are read by calling them like a function: input.n(), not input.n
  • Referring to an input creates a reactive link between that input and the rendering function
  • When the input changes, the rendering function will re-execute
  • You can use multiple inputs in the same rendering function

Your turn

Go to exercises/3-add-filter or work through exercises 1.6-1.9 locally.

Recap

Agenda

  • Setup

  • Hello Shiny

  • The user interface

  • The server

  • Recap

Recap

Most Shiny app development consists of variations of these three things:

  1. Add UI elements
  2. Add rendering functions
  3. Connect inputs and outputs

Your turn

Go to exercises/4-add-plot or work through exercise 1.10 locally.