A Caffeinated Crash Course in Python Python is not Java C Perl The Python Interpreter Type python at the command prompt In windows find the python icon on the start menu Dir and Help help dir Syntax Errors Python Errors show the line number of the error Check the line above if your error makes no sense White Space String Basics Not a mutable data type String can be delimited with either the or More Strings Concatenation uses the You can do math with strings Output Indexing To index into a string specify the position inside square brackets You can index into a string from the end of the string Slicing A Substring of a string is a slice Your head or tail can be a negative index More Slicing You don t need to specify the beginning and end of the string Find the length of a string with len Example Lists Lists in python are made of any data type delimited by commas and surrounded by brackets Lists are mutable More on Lists You can index into lists You can slice lists Modifying Lists You can add lists And append to them List Methods sort sorts the list in place returns nothing sorted does not modify the list returns new sorted list reverse reverses the list in place returns nothing String Formatting The operator substitutes values into a string s and d are placeholders for the values d makes sure it s a number s has d letters colorless len colorless becomes the string colorless has 9 letters Converting from Strings to Lists Join a list to make a string Split a string to make a list For and If If statements For Statements List Comprehensions Applies a function to every element of a list Dictionaries Hash maps things to things Even More Dictionaries Example Letter Frequencies Classes Importing and the Python path Import using the import command You can import everything from a module using the syntax from module import Files Filename home havasi input txt input open Filename r output open Filename out w for line in input readlines input write Cows n input close output close Resources Python org NLTK Python Tutorial http nltk org doc en programming html IDLE Windows Development Env http www python org idle