Copying Data into Excel

The final example is the most involved but illustrates a powerful approach for blending the data analysis of python with the user interface of Excel.

It is possible to build complex excel with pandas but that approach can be very laborious. An alternative approach would be to build up the complex file in Excel, then do the data manipulation and copy the data tab to the final Excel output.

Here is an example of the Excel dashboard we want to create:

Yes, I know that pie charts are awful but I can almost guarantee that someone is going to ask you to put one in the dashboard at some point in time! Also, this template had a pie chart and I decided to keep it in the final output instead of trying to figure out another chart.

It might be helpful to take a step back and look at the basic process the code will follow:

Let%u2019s get started with the code.

import win32com.client as win32
import pandas as pd
from pathlib import Path

# Read in the remote data file
df = pd.read_csv("https://github.com/chris1610/pbpython/blob/master/data/sample-sales-tax.csv?raw=True")

# Define the full path for the data file file
data_file = Path.cwd() / "sales_summary.xlsx"

# Define the full path for the final output file
save_file = Path.cwd() / "sales_dashboard.xlsx"

# Define the template file
template_file = Path.cwd() / "sample_dashboard_template.xlsx"

In the section we performed our imports, read in the data and defined all three files. Of note is that this process includes the step of summarizing the data with pandas and saving the data in an Excel file. We then re-open that file and copy the data into the template. It is a bit convoluted but this is the best approach I could figure out for this scenario.

Next we perform the analysis and save the temp Excel file:

# Do some summary calcs
# In the real world, this would likely be much more involved
df_summary = df.groupby('category')['quantity', 'ext price', 'Tax amount'].sum()

# Save the file as Excel
df_summary.to_excel(data_file, sheet_name="Data")

Now we use COM to merge the temp output file into our Excel dashboard tab and save a new copy:

# Use com to copy the files around
excel = win32.gencache.EnsureDispatch('Excel.Application')
excel.Visible = False
excel.DisplayAlerts = False

# Template file
wb_template = excel.Workbooks.Open(template_file)

# Open up the data file
wb_data = excel.Workbooks.Open(data_file)

# Copy from the data file (select all data in A:D columns)
wb_data.Worksheets("Data").Range("A:D").Select()

# Paste into the template file
excel.Selection.Copy(Destination=wb_template.Worksheets("Data").Range("A1"))

# Must convert the path file object to a string for the save to work
wb_template.SaveAs(str(save_file))

The code opens up Excel and makes sure it is not visible. Then it opens up the dashboard template and data files. It uses the Range("A:D").Select() to select all the data and then copies it into the template file.

The final step is to save the template as a new file.

This approach can be a very convenient shortcut when you have a situation where you want to use python for data manipulation but need a complex Excel output. You may not have an apparent need for it now but if you ever build up a complex Excel report, this approach is much simpler than trying to code the spreadsheet by hand with python.