How do you... Define a Graphing Function

Question

For Data Analytics & using Python. I came across this code(below) and my question is... did the user copy and paste this from somewhere or do I define a graphing function from scratch??????

Using plotly (first time using plotly)

Very new to Python

def make_graph(stock_data, revenue_data, stock):
    fig = make_subplots(rows=2, cols=1, shared_xaxes=True, subplot_titles=("Historical Share Price", "Historical Revenue"), vertical_spacing = .3)
    fig.add_trace(go.Scatter(x=pd.to_datetime(stock_data.Date, infer_datetime_format=True), y=stock_data.Close.astype("float"), name="Share Price"), row=1, col=1)
    fig.add_trace(go.Scatter(x=pd.to_datetime(revenue_data.Date, infer_datetime_format=True), y=revenue_data.Revenue.astype("float"), name="Revenue"), row=2, col=1)
    fig.update_xaxes(title_text="Date", row=1, col=1)
    fig.update_xaxes(title_text="Date", row=2, col=1)
    fig.update_yaxes(title_text="Price ($US)", row=1, col=1)
    fig.update_yaxes(title_text="Revenue ($US Millions)", row=2, col=1)
    fig.update_layout(showlegend=False,
    height=900,
    title=stock,
    xaxis_rangeslider_visible=True)
    fig.show() 

Answer 1

If I understand what you're asking, you are wondering where functions and methods inside the make_graph function are coming from – some import statements might clear things up for you:

import pandas as pd
from plotly.subplots import make_subplots
import plotly.graph_objects as go

def make_graph(stock_data, revenue_data, stock):
    fig = make_subplots(rows=2, cols=1, shared_xaxes=True, subplot_titles=("Historical Share Price", "Historical Revenue"), vertical_spacing = .3)
    fig.add_trace(go.Scatter(x=pd.to_datetime(stock_data.Date, infer_datetime_format=True), y=stock_data.Close.astype("float"), name="Share Price"), row=1, col=1)
    fig.add_trace(go.Scatter(x=pd.to_datetime(revenue_data.Date, infer_datetime_format=True), y=revenue_data.Revenue.astype("float"), name="Revenue"), row=2, col=1)
    fig.update_xaxes(title_text="Date", row=1, col=1)
    fig.update_xaxes(title_text="Date", row=2, col=1)
    fig.update_yaxes(title_text="Price ($US)", row=1, col=1)
    fig.update_yaxes(title_text="Revenue ($US Millions)", row=2, col=1)
    fig.update_layout(showlegend=False,
    height=900,
    title=stock,
    xaxis_rangeslider_visible=True)
    fig.show() 

When you call the function make_graph, it uses the Plotly library's make_subplots function to create an object fig which is a Plotly graph object. All graph objects (such as fig) have the methods add_trace, update_xaxes, update_yaxes, update_layout, and show (as well as other methods) which can be called using dot notation.

The last line fig.show() will use a default renderer (e.g. your browser) to display the figure.

Your textbook very likely includes some sample code to call the make_graph function. I think running this function and looking at the output may help clear things up for you as well.