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PyIO
(read: pai-o)
Python Module for Input-Output Analysis
“Leontief believed that the economy can be broken down into sectors [whose] interrelationship can be described in the form of a mathematical matrix…called an “input-output analysis.” Leontief’s initial set of sectors led to a 12x12 matrix…to invert that … it took him [Cornfield] about a week, and the end result was the conclusion that the number of sectors had to be expanded. …[W]ith trepidation, they [Leontief and Cornfield] ended with the simplest matrix they thought would be feasible, a 24x24 matrix. [It is estimated] that it would take him several hundred years of seven-day work-weeks to invert…” [words in brackets added]
David Salsburg (2001), The Lady Tasting Tea, pp. 177-8.
That was in the 1940s. Nowadays, inverting a matrix with 100 rows and columns is of no significant problem. On the other hand, input-output analysis has reached a very stimulating level requiring more extensive computation beyond inverting a matrix. The module we prepare here introduces an environment where IO analysis may be conducted in an open and free, yet extensive, computing environment. It is expected that there will be more and more researcher joining this environment, allowing for greater use and access to the IO analysis.
PyIO is a module for Input-Output analysis, written in Python, a general-purpose open source computer programming language. The punch line: Python is freely downloadable and open source means you can actually look at the code, change and distribute it further if you want. One best way to find the latest version is by looking at the official Python website http://www.python.org/.
At this moment, there are several functions available comprising basic input-output analysis. There are as follows:
- Inputting input-output data
- Leontief and Ghoshian inverse
- Impact analysis
- Multiplier analysis: output, income, employment, input
- Updating matrix: regional supply percentage, location quotient
- Updating matrix: RAS method
- Key sector analysis
- Output decomposition analysis
- Multiplier product matrix analysis
- Extraction method analysis
- Push-pull analysis
- IO table aggregation
- Field of influence
You can download the PyIO by clicking here. There are four files in the zip file: pyio.py, run_pyio.py (these two are the main files for PyIO application), PyIOmanual.pdf (the PyIO manual), and data.zip (containing files used in the examples in PyIOmanual.pdf). You can copy the first two files to your working directory, and start the PyIO session from there by double-clicking the run_pyio.py.
The manual to the PyIO module is written by Suahasil Nazara, Carolyn Dong Guo, Geoffrey Hewings, and Chokri Dridi (2003) and is published as a REAL Discussion Paper 03-T-23. Please make appropriate reference to this manual if you are using the code.
I want to install Python to run the PYIO. What should I do?
While we are aware that Python is frequently updated –at the moment this website is created, version 2.3 (beta) is the latest there—we suggest users to use Python version 2.2. We actually heard that PyIO also works fine with version 2.3, but no thorough test is done for that.
The installation of Python should be done in the three steps as the following:
First, install Python version 2.2. For Windows user, you should download Python-2.2.3.exe and double click this file to install Python version 2.2.
Second, install the Windows Extension for Python version 2.2. Download Mark Hammond’s Python for Windows Extensions (http://starship.python.net/crew/mhammond/) which for Python version 2.2 is named win32all-152.exe.
Third (only after these two files are properly installed in your computer), you should also install the Numerical Python (Numpy), a module for numerical array computation. Windows user should install Numeric-23.0.win32-py2.2.exe. Once again, Numpy should be installed only when you have the first two files properly installed in your computer.
Having installed all of the three files, you are ready to use PyIO. You can start by double clicking run_pyio.py.
What hardware is required?
Any Pentium-level computer should be able to run Python and PyIO. The limit is more on the software. The current version of PyIO is intended only for Windows user. We are really sorry that we cannot accommodate Mac and Linux users. All of the functions in PyIO offers an output in Microsoft Excel format. If you want this, naturally the Microsoft Excel should be properly installed in your computer. For those who do not want Excel output, PyIO will automatically write the results in an ASCII text file.