Introduction to Python

At the 2012 NCED Summer Institute in Earth Surface Dynamics (SIESD), we realized that there is a large community desire to transition to open source programming languages and tools, but that a roadblock is the lack of a coherent set of information to allow individual scientists to act on these desires without needing to invest a large amount of time. Here I will introduce programming in Python, a fairly intuitive interpreted programming language, and some basic finite difference numerical methods through a simple example of a linear-diffusive hillslope.

Python

What is it?

Python is a general-purpose, high-level, interpreted programming language. This means that:

• General-purpose: You can use Python for numerical analysis, mapping and GIS, web design, interfacing with computer hardware, plotting and graphics, database management, image processing, and certainly lots of additional applications that scientists do not often have need to use. These applications are embodied in specific modules that can be imported into your Python script.
• High-level: Python uses array operations and pre-constructed functions to allow you to write your code in many fewer lines than would be required in a low-level language like C.
• Interpreted: Some languages use a compiler to convert what you write into bytecode that can be interpreted by the computer. Python is "interpreted", meaning that it calls pre-compiled chunks of code that are combined to run the program. It is easier and faster, but can be slower for computationally-intensive applications. However, your own compiled C code can be included in Python scripts for these applications, and the ease of use is a huge advantage!

Downloading and Installing

We will be using Python 2.7, the Scipy/Numpy package that includes tools for many common scientific and numerical applications and n-dimensional arrays, and the Matplotlib package that comprises a range of plotting tools.

Linux

package manager

(Very) helpful tools

• iPython
• Spyder