A Caffeinated Crash Course inPythonPython is not….• Java• C• PerlThe Python Interpreter• Type “python” at the command prompt• In windows, find the python icon on thestart menuDir and Helphelp()dir()Syntax Errors• Python Errors show the line number ofthe error• Check the line above if your error makesno senseWhite SpaceString 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!OutputIndexing• To index into a string, specify the positioninside square brackets• You can index into a string from the “end” ofthe string.Slicing• A Substring of a string is a slice• Your head or tail can be a negativeindexMore Slicing• You don’t need to specify the beginningand end of the string• Find the length of a string with len()ExampleLists• Lists in python are made of any datatype delimited by commas andsurrounded by brackets.• Lists are mutableMore on Lists• You can index into lists• You can slice listsModifying Lists• You can add lists• And append to themList Methods• sort - sorts the list in place, returns nothing• sorted - does not modify the list, returns newsorted list• reverse - reverses the list in place, returnsnothingString Formatting• The % operator substitutes values into astring• %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 9letters”Converting fromStrings to Lists• Join a list to make a string• Split a string to make a listFor and If• If statements• For StatementsList Comprehensions• Applies a function to every element of alistDictionaries• Hash - maps things to things!Even More DictionariesExample: Letter FrequenciesClassesImporting and the Python path• Import using the import command• You can import everything from amodule using the syntax “from<module> import *”FilesFilename = “/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.)–