How to develop a Python tool for generating custom workout plans based on user input?

To develop a Python tool for generating custom workout plans based on user input, we need to have a general knowledge of Python programming and its tools like pandas, numpy, and flask for web development.

Here's a general example of how we might accomplish this:

Step 1: Setting up the development environment

Make sure Python is installed on your system. You can download it from the official website.

Create a new directory for the project and create a virtual environment. This can be done using the following commands:

$ mkdir workout-plan-generator
$ cd workout-plan-generator
$ python3 -m venv env

Activate the virtual environment:

$ source env/bin/activate

Install the necessary packages:

$ pip install flask pandas numpy

Step 2: Creating the workout plan data

Let's say we have an assortment of workouts categorized by the part of the body they target. This data can be created with pandas DataFrames.

Create a file named workout_data.py and put the following data:

import pandas as pd

workouts = pd.DataFrame({
    'workout': ['push-ups', 'squats', 'lunges', 'crunches', 'planks', 'biceps'],
    'target': ['chest', 'legs', 'legs', 'abs', 'abs', 'arms']
})

Step 3: Creating the response function

We can create a function that takes user input on which part of the body the user wants to focus on, and returns a few workouts that targets that body part.

Create a new file named generate_plan.py and insert the following Python code:

import workout_data

def generate_workout_plan(body_part):
    suitable_workouts = workout_data.workouts[workout_data.workouts['target'] == body_part]
    return suitable_workouts.sample(3)['workout'].tolist()

This function takes the user input, filters the DataFrame for the rows that match the target body part, and randomly selects three workouts from them.

Step 4: Creating the web server with Flask

Our tool needs a user interface. Flask is a lightweight web server for Python, which we can use for this.

Create a new file named app.py and insert the following Python code:

from flask import Flask, request, jsonify
import generate_plan

app = Flask(__name__)

@app.route('/generate', methods=['POST'])
def generate():
    body_part = request.json['body_part']

    return jsonify(generate_plan.generate_workout_plan(body_part))

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

This creates a new web server that listens for POST requests at the /generate url. It expects the requests to have JSON data with a 'body_part' field, and returns a JSON response with the generated workout plan.

Step 5: Testing the tool

Now, you can start the server with python app.py and test it by sending a POST request. You can use tools like curl or Postman to send the POST request.

Start the server:

$ python app.py

You've just created a basic workout plan generator! This is of course a very basic example and real-world applications would require more advanced coding, possibly machine learning for more suitable workout plans, integrating with a database to keep track of user progress, adding authentication for users, and so forth.