DatePickerRange for a period current year vs. same period in previous year

📊 Plotly Python
,
1

Hello i am to select data for a particular range of dates and would like to compare the same period with previous year. Any leads on how to go about it?

Thanks

2

I have tried working on this but i get this error!

Callback error updating testDate.children
AttributeError: ‘str’ object has no attribute ‘year’

Here is the code i am working with

import pandas as pd
import dash
import datetime as dt
import calendar
from dash import Dash, html, dcc, Input, Output
sales = pd.read_csv('sales_data.csv', parse_dates=['date'])
app = Dash(__name__)
app.layout = html.Div([

    # Date Picker
    html.Div([
            dcc.DatePickerRange(
            id='date_filter',
            end_date_placeholder_text='End Date',
            first_day_of_week=1,
            month_format='MMMM Y',
            minimum_nights=2,
            persistence_type='session',
            updatemode='singledate')], ),
    html.Div([
             html.Div([
                 html.Div(id='testDate'),
             ], className='card'),])
])


@app.callback(
    Output('testDate', 'children'),
    [Input('date_filter', 'start_date'),
     Input('date_filter', 'end_date'),
     ]
)
def update_output(start_date, end_date):

    if not start_date or not end_date:
        raise dash.exceptions.PreventUpdate
    else:
        # Sales current year
        cy_total_sales = sales[(sales['date'] >= start_date) & (sales['date'] <= end_date)]['sales'].sum()

        # Time Delta
        # cy_start_date = start_date
        # cy_end_date = end_date
        period = 12

        # Previous Year corresponding start and end years
        py_start_year = start_date.year + (start_date.month - 1 + period) // 12
        py_end_year = end_date.year + (end_date.month - 1 + period) // 12

        # Previous Year corresponding start and end months
        py_start_month = (start_date.month - 1 + period) % 12 - 1
        py_end_month = (end_date.month - 1 + period) % 12 - 1

        # Previous Year corresponding start and end dates
        py_start_date = min(start_date.day, calendar.monthrange(py_start_year, py_start_month)[1])
        py_end_date = min(end_date.day, calendar.monthrange(py_end_year, py_end_month)[1])

        # Sales current year
        py_total_sales = sales[(sales['date'] >= py_start_date) &
                               (sales['date'] <= py_end_date)]['sales'].sum()
        return [

            html.P(py_start_date),
            html.P(py_end_date)
        ]


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

Data format
date sales
0 2022-04-12 117
1 2023-05-17 102
2 2022-03-31 108
3 2023-05-10 130
4 2023-10-07 144
… … …
148 2022-12-02 117
149 2022-04-30 111
150 2023-10-11 119
151 2022-01-23 117
152 2023-09-10 140

what could be the problem? thanks in advance

3

start_date and end_date are strings. You need to convert them to a datetime object if you want to get the year, month, etc.

import datetime

start_date_str = '2024-09-23'
start_date_dt = datetime.datetime.strptime(start_date_str, '%Y-%m-%d')
print(start_date_dt.year)
4

Thanks PyGuy, This has worked.

The only challenge I have now is the dates are printed in this format. ‘2023-09-02T00:00:00’
thus below error
ValueError: unconverted data remains: T13:10:55.860229