CHEM10121: Introduction to Scientific Programming in Python: Glossary

Key Points

Introduction
  • You can assign the values of several variables at once.

  • Multiple values can be stored togeother in a list, which is ordered, or a dictionary, which is not ordered.

File Parsing
  • Indentation is very important in for loops and if statements. Don’t forget the : and to indent the items in the loop.

  • You should use the os.path module to work with file paths.

  • One of the most flexible ways to read in the lines of a file is the readlines() function.

  • An if statement can be used to find a particular string within a file.

  • The split() function can be used to seperate the elements of a string.

  • You will often need to recast data into a different data type when it was read in as a string.

Processing Multiple Files and Writing Files
  • Use the glob function in the python library glob to find all the files you want to analyze.

  • You can have multiple for loops nested inside each other.

  • Python can only print strings to files.

  • Don’t forget to close files so python will actually write them.

Working with Tabular Data
  • If you are reading in a file that is mostly numerical data, there are better ways to read in the data than using readlines().

  • The notation to refer to a particular element of an array is array_name[row,column].

  • Typically, you should not write a function to perform a standard math operation. The function probably already exists in numpy.

Plotting and Data Visualization
  • The matplotlib library is the most commonly used plotting library.

  • You can import libraries with shorthand names.

  • You can save a figure with the savefig command.

  • Matplotlib is highly customizable. You can change the style of your plot, and there are many kinds of plots.

Writing Functions
  • Functions make your code easier to read, more reuseable, more portable, and easier to test.

  • If a function returns True or False, you can use it in an if statement as a condition.

The Atomic Simulation Environment: Python for Chemistry
  • The ASE can be used to read, write and manipulate most common chemical formats.

  • Calculators in ASE interface with a variety of compuational chemistry programs.

  • Because the ASE is in python, we can use it to do a chemical calculation and use other python modules (e.g. numpy, matplotlib) to use the results of calculations.

Glossary

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