Python is a dynamic object-oriented programming language with extensive standard libraries. These notes summarize the Python 3.0 tutorial.

• python/python3.0 is the command-line interpreter with readline where available.
• python -c command runs a single command.
• sys.argv is a list of strings with the script if any in sys.argv[0]
• »> prompts for a line . … prompts for a continuation of a previous line
• PYTHONSTARTUP can point to a file of startup commands
• Expressions are evaluated and printed.
• The last printed expression is assigned to _ .

• Comments start with # .
• Variables can be assigned (using = ) without being defined but must be assigned before being used.
• a,b = c,d does a multiple assignment.
• Imaginary numbers can be created using complex(a,b) or a+bJ. .real and .imag will extract real and imaginary parts.
• print(“a”,“b”,end=“”) prints a b with no newline at the end.

• list=[1 ,'a' , “b”] is a list of three items.
• list[4] is 4th element. list[2:4] is second and third elements. list[:2] is first 2 elements. list[2:] is third element to last one. list[:] is the whole list.
• Negative indexes count from last element.
• List slices can be modified. list[3:3] can be used to insert elements at position 3. list.append() appends to the list.
• len(list) returns length of the list.
• Lists can be nested.

• Strings can be enclosed with double or single-quotes.
• \ in a string by itself goes to the next line but does not insert a newline (\n does).
• A raw string - r“” does no escaping.
• + concatenates strings, * repeats them .
• A string can be treated as a list of letters.
• But strings can't be modified using slices or indexes.
• String methods include strip, format, capitalize etc.
• format-string % (tuple) allows use of printf formatting strings. Also string.format() .