PYTHON LECTURE OUTLINE

(0) Disclaimers

- there is no "one true/best language"; you will have to learn others
- we will probably run out of time; can continue in a workshop
  outside of class


(1) Resources

- docs.python.org
  - "index" is most useful
  - "Library Reference" is next in usefulness
- stuff I put up on Assignment 1 page for BME 205:
    Tutorial docs:
      http://docs.python.org/tutorial/interpreter.html
      http://docs.python.org/tutorial/introduction.html
      http://docs.python.org/tutorial/controlflow.html
      http://docs.python.org/tutorial/inputoutput.html
    Understanding strings (and more generally, sequences):
      http://docs.python.org/library/stdtypes.html#string-methods
      http://docs.python.org/library/stdtypes.html#string-formatting-operations
      http://docs.python.org/library/stdtypes.html#sequence-types-str-unicode-list-tuple-buffer-xrange
    Useful standard library modules:
      http://docs.python.org/library/string.html
      http://docs.python.org/library/re.html
      http://docs.python.org/library/sys.html
- Python in a Nutshell (useful for advanced users only)
- stuff to which I refer throughout this lecture


(2) Starting it up

- Python versions
- Make sure to specify "python2.6" on SOE machines
- Command-line interpreter
  - using it as a calculator; basic caveats about type conversion
  - whitespace only matters for indentation and EOL
  - history (readline support)
  - Ctrl+D to exit


(3) Some Python types

- type overview (draw table for type conversion syntax versus shorthand)
  - int, float, list, string, tuple, dict, None

- basics: int and float

- an aside about the Python data model
  - everything is a reference; the object to which we refer has the type
  - what is an object?  what is a method?  why not just use functions?
  - the concept of "binding"
  - re-binding: powerful but dangerous!
    - caveat about re-binding built-in functions like "type" and "chr" and "next":
      see http://docs.python.org/library/functions.html
      and http://docs.python.org/library/stdtypes.html
      - or use interpreter to tell if a build-in function or type
- caveats about "modifying" a reference
  - you don't modify references other than re-binding;
    you modify the object TO WHICH the reference(s) point

- some standard types
  (with special attention paid to the binding/reference model)
  - see http://docs.python.org/reference/datamodel.html#the-standard-type-hierarchy

  - None type

  - sequences: mutable and immutable
    - lists (mutable):
      - creating
      - .append()
      - .sort() versus sorted()
        - in place (no return value) versus new copy returned
        - sorting 'listOrig' and 'listNew' (test understanding of references)
      - min() and max()
      - an aside: method versus function
      - looking at contents; modifying contents
      - lists store REFERENCES (which can get rebound)
      - slices
        - understanding how Python iterates over ranges
          - explains why out-of-bounds is allowed
        - all Python ranges (i,j,k) ALWAYS:
          - init to i
          - steps of i+k, i+2k, i+3k...
          - terminate BEFORE j (j-1 or j+1, depending on sign of k)
        - left-hand slices versus right-hand slices
      - list comprehensions
        - only in Python 2.5 or newer!

    - strings (immutable): single versus double quotes
      - all slice operations on lists can also be done on strings
      - some string methods: {l,r}strip, join, replace

    - tuples (immutable)
      - useful for:
        - string formatting (will cover later)
        - as keys to dictionaries

  - dictionaries (actually a "mapping" type)
    - what can be a key?  any hashable type
      - all immutable types can be a key: string, tuple, number
    - don't confuse with lists

  - brief note about other types: sets, modules, callables, classes, files, etc.


(4) Printing and string formatting

- print keywords
- string formatting with % operator and tuples


(5) Writing your first Python program

- shebang
- chmod
- comments
- imports
- sys module
  - sys.argv
  - sys.exit()
- printing to STDERR
- whitespace
- conditionals
- assert
- loops (file I/O)
- simple comparator functions
- iterating through lists of tuples


(6) Additional stuff - ONLY OF THERE IS TIME LEFT

- more on iterators
  - a special note about xrange() and loops

- function parameters: positional, named, extra, defaults
  - caveat about modifying default params


(7) Questions and feedback

- another workshop outside of class time?