DePaul University



Mini-API and Cheat SheetStringss.capitalize()Returns the capitalized version of s. # 'hello' => 'Hello's.lower()Returns the lower case version of s. # 'HELLO' => 'hello's.swapcase()Returns the swapped-case version of s. # 'Hello' => "hELLO"s.title()Returns the title case version of s. # 'hello world' => 'Hello World's.upper()Returns the upper case version of s. # 'hello' => 'HELLO's.replace(s2, s3)Replace s2 with s3 in s. Returns the string.s2 in sReturn true if s contains s2s + s2Concatenates s and s2len(s)Returns length of smin(s)Returns smallest character of smax(s)Returns largest character of ss * integerReturns 'integer' copies of 's' concatenated # 'hello' => 'hellohellohello's2 not in sReturn true if s does not contain s2s.find(s2)Find and return lowest index of s2 in s. Returns -1 if not present.s[index]Returns character at index of ss.count(s2)Returns count of s2 in ss.index(s2)Returns lowest index of s2 in s (but raises ValueError exception if not found)s.islower()Return true if s is lowercases.isupper()Return true if s is uppercases.split(sep, maxsplit)Return list of s split by sep with leftmost maxsplits performeds[i:j]Slice of s from i to j Dictionaries emptyDict = {} #creates a new empty dictionarythisdict = {'a':1, 'b':23, 'c': 'eggs'} #new dictionary with some datathisdict['a'] #returns 1 thisdict.keys() #returns ['a', ,'b', 'c'] thisdict.values() #returns [1, 23, 'eggs'] thisdict.items() #returns [('a', 1), ('b',23), ('c', 'eggs')] Deleting: del thisdict['b'] Retrieving: thisdict.has_key('e') #returns False 'c' in thisdict #returns True 'paradimethylaminobenzaldehyde' in thisdict #returns FalseSome important methods of class list:sort() #returns a sorted copy of the listappend(x) #appends 'x' to the listremove(item)#removes item from the list if presentOther useful methods / operators for use with lists:9 in someList #returns Falselen(list) #returns the number of items in listOutline of a function:def identifier( <parameters> ):code here… Optional return statementOutline of if/else block:if conditionalA and conditionalB:code hereelif conditionalC or conditionalD:code hereelse:something elseOutline of exception handling block:try:Do somethingexcept <optional exception types>:code to handle the exception goes hereTuplesemptyTuple = ()nonemptyTuple = (3,'yellow', 48)nonemptyTuple[2] #returns 48Format String:favColor = 'blue'name = 'bob'sentence = "{}'s favorite color is {}".format(name, favColor)for loops & range()Say you have a list called "collection", the following will output all items in that list:for item in collection:print(item)for i in range(2,5): print(i) #will print 2,3,4 (on separate lines)while loops:while <conditional>:Code CodeCodeMethods for working with input file objects:fin = open(some_file,'r')fin.read() #reads some_file as one stringfin.readline() #reads in the next line ahead of the cursor, returns a stringfin.readlines() #reads in all lines beginning at the cursor; returns a list A few useful functions from the 'random' module:random.randint(1,n) #returns a random integer between 1 and nrandom.shuffle(some_list) #returns the list in a new orderrandom.choice(some_list) #returns a random value out of some_listA few useful functions from the 'math' module:math.ceil(x) #returns the ceiling of x e.g. math.ceil(33.2) returns 34math.floor(x) #returns the ceiling of x e.g. math.floor(33.9) returns 33math.pow(x,y) #returns the x to the power of y. of x e.g. math.pow(3,2) returns 9math.sqrt(x) #returns the square root of x e.g. math.sqrt(25) returns 5.0PRECEDENCE TABLE OperatorDescription(expressions...), [expressions...], {key:datum...}, `expressions...`Binding or tuple display, list display, dictionary display, string conversionx[index], x[index:index], x(arguments...), x.attributeSubscription, slicing, call, attribute reference**Exponentiation [8]+x, -x, ~xPositive, negative, bitwise NOT*, /, //, %Multiplication, division, remainder+, -Addition and subtraction<<, >>Shifts&Bitwise AND^Bitwise XOR |Bitwise OR in, not in, is, is not, <, <=, >, >=, <>, !=, ==Comparisons, including membership tests and identity tests,not xBoolean NOTandBoolean ANDorBoolean ORlambdaLambda expressionCommon Sequence OperationsThe following methods work on most sequence types – both mutable and immutable: (e.g. lists, tuples, etc). OperationResultx?in?sTrue?if an item of?s?is equal to?x, else?Falsex?not?in?sFalse?if an item of?s?is equal to?x, else?Trues?+?tthe concatenation of?s?and?ts[i]ith item of?s, origin 0s[i:j]slice of?s?from?i?to?jlen(s)length of?smin(s)smallest item of?smax(s)largest item of?ss.index(x])index of the first occurrence of?x?in?s?s.count(x)total number of occurrences of?x?in?sThe functions below only work on mutable sequence types (e.g. lists)OperationResults[i]?=?xitem?i?of?s?is replaced by?xdel?s[i:j]same as?s[i:j]?=?[]del?s[i:j:k]removes the elements of?s[i:j:k]?from the lists.append(x)appends?x?to the end of the sequence (same ass[len(s):len(s)]?=?[x])s.clear()removes all items from?s?(same as?del?s[:])s.insert(i,?x)inserts?x?into?s?at the index given by?i?s.pop([i])retrieves the item at?i?and also removes it from?ss.remove(x)remove the first item from?s?where?s[i]?==?x ................
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