Create tabular PDF reports with Python, xtopdf and tablib

By Vasudev Ram

Tablib is a Python library that allows you to import, export and manipulate tabular data.

I had come across tablib a while ago. Today I thought of using it with xtopdf, my Python library for PDF creation, to generate PDF output from tabular data. So I wrote a program, TablibToPDF.py, for that. It generates dummy data for student grades (for an examination), then puts that data into a tablib Dataset, and then exports the contents of that Dataset to PDF, using xtopdf. Given the comments in the code, it is mostly self-explanatory. I first wrote the program in an obvious/naive way, and then improved it a little by removing some intermediate variables, and by converting some for loops to list comprehensions, thereby shortening the code by a few lines. Here is the code for TablibToPDF.py:

"""
TablibToPDF.py
Author: Vasudev Ram
Copyright 2014 Vasudev Ram - www.dancingbison.com
This program is a demo of how to use the tablib and xtopdf Python libraries 
to generate tabular data reports as PDF output.
Tablib is at: https://tablib.readthedocs.org/en/latest/
xtopdf is at: https://bitbucket.org/vasudevram/xtopdf
and info about xtopdf is at: http://slides.com/vasudevram/xtopdf or 
at: http://slid.es/vasudevram/xtopdf
"""

import random
import tablib
from PDFWriter import PDFWriter

# Helper function to output a string to both screen and PDF.
def print_and_write(pw, strng):
    print strng
    pw.writeLine(strng)

# Set up grade and result names and mappings.
grade_letters = ['F', 'E', 'D', 'C', 'B', 'A']
results = {'A': 'Pass', 'B': 'Pass', 'C': 'Pass', 
    'D': 'Pass', 'E': 'Pass', 'F': 'Fail'}

# Create an empty Dataset and set its headers.
data = tablib.Dataset()
data.headers = ['ID', 'Name', 'Marks', 'Grade', 'Result']
widths = [5, 12, 8, 8, 12] # Display widths for columns.

# Create some rows of student data and use it to populate the Dataset.
# Columns for each student row correspond to the header columns 
# shown above.

for i in range(20):
    id = str(i).zfill(2)
    name = 'Student-' + id
    # Let's grade them on the curve [1].
    # This examiner doesn't give anyone 100 marks :)
    marks = random.randint(40, 99)
    # Compute grade from marks.
    grade = grade_letters[(marks - 40) / 10]
    result = results[grade]
    columns = [id, name, marks, grade, result]
    row = [ str(col).center(widths[idx]) for idx, col in enumerate(columns) ]
    data.append(row)

# Set up the PDFWriter.
pw = PDFWriter('student_grades.pdf')
pw.setFont('Courier', 10)
pw.setHeader('Student Grades Report - generated by xtopdf')
pw.setFooter('xtopdf: http://slides.com/vasudevram/xtopdf')

# Generate header and data rows as strings; output them to screen and PDF.

separator = '-' * sum(widths)
print_and_write(pw, separator)

# Output headers
header_strs = [ header.center(widths[idx]) for idx, header in enumerate(data.headers) ]
print_and_write(pw, ''.join(header_strs))
print_and_write(pw, separator)

# Output data
for row in data:
    print_and_write(pw, ''.join(row))

print_and_write(pw, separator)
pw.close()

# [1] http://en.wikipedia.org/wiki/Grading_on_a_curve
# I'm not endorsing the idea of grading on a curve; I only used it as a 
# simple algorithm to generate the marks and grades for this example.

You can run it with:

$ python TablibToPDF.py

It sends the tabular output that it generates, to both the screen and to a PDF file named student_grades.pdf.
Here is a screenshot of the generated PDF file, opened in Foxit PDF Reader:

The program that I wrote could actually have been written without using tablib, just with plain Python lists and/or dictionaries. But tablib has some additional features, such as dynamic columns, export to various formats (but not PDF), and more - see its documentation, linked near the top of this post. I may write another blog post later that explores the use of some of those tablib features.

- Enjoy.

Vasudev Ram - Python consulting and training - Dancing Bison Enterprises

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