More realistic file import example

[gshotwell]

Typically when users use file import they import the file, process it, and then send it to several renderers. Our example uses a fairly unrealistic pattern of reading in a file and sending it to an HTML table which leads people a bit astray because it's a pattern which doesn't generalize very well.

We should add an example which reads the data into a reactive value:

• Data is imported and sent to reactive value
• Checkboxes give people some options (row count, column count, column names)
• A table is rendered with their choices and the stats from the data

[adejumoridwan]

Hi @gshotwell I would like to take this issue, but I will appreciate some guidance. I am a new contributor.

[gshotwell]

Awesome!

You should be able to add a different example to the doc string, just make sure that it runs in shiny live.

Here's the I've I came up with in the Discord in case it's a helpful starting point:

from shiny import ui, render, reactive, App, req
import pandas as pd

app_ui = ui.page_fluid(
    ui.input_file("file", "File", accept=".csv"),
    ui.output_table("summary")
) 

def server(input, output, session):
    # Reading in the data into a reactive calcuation makes it easier to work with
    @reactive.Calc
    def parsed_file():
        file = input.file()
        if file is None:
            # Returning an empty dataframe is a bit simpler than the conditional UI
            return pd.DataFrame()
        return pd.read_csv(file[0]["datapath"])
    
    @output
    @render.table
    def summary():
        # Your applicaton logic would pick it up from here
        return parsed_file()

app = App(app_ui, server)

[adejumoridwan]

Thanks, please can you assign the issue to me.

[adejumoridwan]

Hi @gshotwell here is the example. Does this look good to go?

import pandas as pd

from shiny import App, reactive, render, ui

app_ui = ui.page_fluid(
    ui.input_file("file", "File", accept=".csv"),
    ui.input_checkbox("row_count", "Row count", False),
    ui.input_checkbox("column_count", "Column count", False),
    ui.input_checkbox("column_names", "Column names", False),
    ui.output_table("summary"),
)


def server(input, output, session):
    # Reading in the data into a reactive calcuation makes it easier to work with
    @reactive.Calc
    def parsed_file():
        file = input.file()
        if file is None:
            # Returning an empty dataframe is a bit simpler than the conditional UI
            return pd.DataFrame()
        return pd.read_csv(file[0]["datapath"])

    @output
    @render.table
    def summary():
        df = parsed_file()

        if df.empty:
            return pd.DataFrame()

        # Get the row count, column count, and column names of the DataFrame
        row_count = df.shape[0]
        column_count = df.shape[1]
        names = df.columns.tolist()
        column_names = ", ".join(str(name) for name in names)

        # Create a new DataFrame to display the information
        info_df = pd.DataFrame(
            {
                "Row Count": [row_count],
                "Column Count": [column_count],
                "Column Names": [column_names],
            }
        )

        # return only selected columns based on input
        inputs = [input.row_count(), input.column_count(), input.column_names()]

        index_of_false = []
        for index, element in enumerate(inputs):
            if not element:
                index_of_false.append(index)

        if index_of_false is not None:
            return info_df.drop(info_df.columns[index_of_false], axis=1)

        return info_df


app = App(app_ui, server)

[gshotwell]

That looks great, my only comment is that I think you can use a checkbox group input instead of the repeated checkboxes. This simplifies the display a fair bit. Do you want to submit a PR with this? It should go here: https://github.com/rstudio/py-shiny/blob/921c16bfa177694853a557f059506c4e5bac992f/shiny/examples/input_file/app.py

import pandas as pd

from shiny import App, reactive, render, ui

app_ui = ui.page_fluid(
    ui.input_file("file", "File", accept=".csv"),
    ui.input_checkbox_group(
        "stats", "Summary Stats", choices=["Row Count", "Column Count", "Column Names"]
    ),
    ui.output_table("summary"),
)


def server(input, output, session):
    @reactive.Calc
    def parsed_file():
        file = input.file()
        if file is None:
            return pd.DataFrame()
        return pd.read_csv(file[0]["datapath"])

    @output
    @render.table
    def summary():
        df = parsed_file()

        if df.empty:
            return pd.DataFrame()

        # Get the row count, column count, and column names of the DataFrame
        row_count = df.shape[0]
        column_count = df.shape[1]
        names = df.columns.tolist()
        column_names = ", ".join(str(name) for name in names)

        # Create a new DataFrame to display the information
        info_df = pd.DataFrame(
            {
                "Row Count": [row_count],
                "Column Count": [column_count],
                "Column Names": [column_names],
            }
        )

        return info_df.loc[:, input.stats()]


app = App(app_ui, server)

[adejumoridwan]

Thanks @gshotwell , made the PR already