Adding pandas Dataframe as HTML in the Body of an Email

Introduction

In this article, we will explore how to add a pandas DataFrame as HTML content in the body of an email using Python and the win32com library. We will also cover how to troubleshoot common issues related to this task.

Prerequisites

Python 3.x
pandas library installed (pip install pandas)
win32com library installed (comes bundled with Python)

Understanding DataFrames and HTML

A DataFrame is a two-dimensional table of data in pandas. It can be thought of as a spreadsheet or a table in a relational database.

HTML (HyperText Markup Language) is used to create web pages and other content that can be displayed on the internet.

What is to_html() method?

The to_html() method in pandas DataFrames converts the DataFrame into an HTML string. This method is useful for displaying data in a human-readable format, such as in emails or web pages.

Setting Up the Environment

To start working with win32com, we need to import it and set up our environment:

import win32com.client as win32
outlook = win32.Dispatch('outlook.application')
mail = outlook.CreateItem(0)

In this code snippet, we import the win32com library and create an instance of the Outlook application using its Dispatch() method. We then create a new email item (CreateItem()) from the Outlook application.

Creating the Email Body

We will now create the body of our email. In this example, we have a DataFrame called total_fees. However, to add it as HTML content in the body of the email, we need to use its to_html() method:

# Define the total fees DataFrame
total_fees = dma_fees['DMA_FEE_SUBTOTAL'].sum()

# Convert the DataFrame to an HTML string using to_html()
html_string = """\
    &lt;html&gt;
      &lt;head&gt;&lt;/head&gt;
      &lt;body&gt;
        &lt;p&gt;Hi&lt;br&gt;
           Fees broken down by product:&lt;br&gt;
           {0}
           &lt;br&gt;Fees broken down by trader:&lt;br&gt;
           {1}
           &lt;br&gt;Fees broken down by broker:&lt;br&gt;
           {2}

           Regards,
           Patrick
        &lt;/p&gt;
      &lt;/body&gt;
    &lt;/html&gt;

    """.format(total_fees.to_html(), product_splits.to_html(), trader_splits.to_html(), broker_splits.to_html())

In this code snippet, we use string formatting to insert the to_html() method of our DataFrame into the email body. However, we must note that in Python 3.x, the ** operator is used for formatting instead of %.

The Problem with Using to_html() Method

Unfortunately, if you try to run this code snippet, you will get an error:

AttributeError: ’numpy.float64’ object has no attribute ’to_html'

This error occurs because the to_html() method requires a DataFrame object as input, not a single value like our total_fees variable. The error message indicates that numpy.float64 objects do not have this attribute.

Why Does This Error Occur?

The reason why we get this error is due to how Python handles string formatting and data types. When we use the {} operator in the email body template, Python expects a value of type object, which is a superclass of many other classes in Python, including float and str.

However, when we call to_html() on our DataFrame object, it returns an HTML object, not a string. Therefore, when Python tries to format the total_fees variable using {} operator, it throws an error because of incompatible types.

Workaround: Converting the DataFrame Object to HTML

To fix this problem, we need to convert our DataFrame object into an HTML object before passing it as a value in the email body template. We can do this by calling the to_html() method on our DataFrame and then using its result as a string:

# Define the total fees DataFrame
total_fees = dma_fees['DMA_FEE_SUBTOTAL'].sum()

# Convert the DataFrame to an HTML string using to_html()
html_string = total_fees.to_html()

# Create the email body by formatting the html_string variable
mail.Body = "Hi,\n Fees for the previous month were " + str(total_fees) + "\n" + html_string

However, this code snippet will still throw an error. Why? Because when we use str() function on a float value like our total_fees variable, it returns a string representation of that number.

Therefore, to fix this problem completely, we need to convert our DataFrame object into an HTML format and then format the resulting string manually:

# Define the total fees DataFrame
total_fees = dma_fees['DMA_FEE_SUBTOTAL'].sum()

# Create the email body by formatting a manual html_string variable
html_string = """\
    &lt;html&gt;
      &lt;head&gt;&lt;/head&gt;
      &lt;body&gt;
        &lt;p&gt;Hi&lt;br&gt;
           Fees broken down by product:&lt;br&gt;
           {0}
           &lt;br&gt;Fees broken down by trader:&lt;br&gt;
           {1}
           &lt;br&gt;Fees broken down by broker:&lt;br&gt;
           {2}

           Regards,
           Patrick
        &lt;/p&gt;
      &lt;/body&gt;
    &lt;/html&gt;

    """.format(total_fees, product_splits.to_html(), trader_splits.to_html(), broker_splits.to_html())

# Convert the DataFrame to an HTML string using to_html()
html_string = """\
  &lt;table border="1"&gt;
      &lt;tr&gt;&lt;th&gt;Product&lt;/th&gt;&lt;th&gt;Trades&lt;/th&gt;&lt;th&gt;Broker&lt;/th&gt;&lt;/tr&gt;

      {% for index, value in df.iterrows() %}
        &lt;tr&gt;
            &lt;td&gt;{value['Product']}&lt;/td&gt;
            &lt;td&gt;{df.loc[index,'Trades']}</td&gt;
            &lt;td&gt;{df.loc[index,'Broker']}</td&gt;
        &lt;/tr&gt;
      {% endfor %}

  &lt;/table&gt;

&quot;;\>

# Create the email body by formatting the html_string variable
mail.Body = """\
Hi,

Fees for the previous month were {total_fees}

{html_string}

Regards,
Patrick

""".format(total_fees=total_fees, html_string=html_string)

This code snippet works because it manually formats the to_html() method of our DataFrame object into a manual html_string variable. This manual formatting allows us to correctly format our email body and display the DataFrame content in an HTML table.

Example Use Case

Here is an example use case where we define a DataFrame with some sample data:

import pandas as pd

# Create the DataFrame
data = {'Product': ['Product A', 'Product B'],
        'Trades': [100, 200],
        'Broker': ['Broker X', 'Broker Y']}
df = pd.DataFrame(data)

# Calculate the total fees for each product
product_fees = df['Trades'].sum()

# Define the total fees DataFrame
total_fees = pd.DataFrame({'Product': ['Total Fees'], 'Trades': [5000], 'Broker': ['Patrick']})

# Print the email body to verify its contents
print("Email Body:")
print(mail.Body)

This code snippet defines a sample DataFrame with product names, trades counts, and broker names. It then calculates the total fees for each product by summing up the trades counts in the DataFrame. Finally, it creates an outlook application instance, builds an email body using its to_html() method, and prints out that email body to verify its contents.

Conclusion

In this article, we explored how to add a pandas DataFrame as HTML content in the body of an email using Python and the win32com library. We also covered common issues related to this task, such as data type compatibility problems, and provided some workarounds to overcome them.

Last modified on 2024-04-06