python

Table 3: Methods Provided by Lists in Python

Method Name	Use	Explanation
append	alist.append(item)	Adds a new item to the end of a list
insert	alist.insert(i,item)	Inserts an item at the ith position in a list
pop	alist.pop()	Removes and returns the last item in a list
pop	alist.pop(i)	Removes and returns the ith item in a list
sort	alist.sort()	Modifies a list to be sorted
reverse	alist.reverse()	Modifies a list to be in reverse order
del	del alist[i]	Deletes the item in the ith position
index	alist.index(item)	Returns the index of the first occurrence of item
count	alist.count(item)	Returns the number of occurrences of item
remove	alist.remove(item)	Removes the first occurrence of item

Table 4: Methods Provided by Strings in Python

Method Name	Use	Explanation
center	astring.center(w)	Returns a string centered in a field of size w
count	astring.count(item)	Returns the number of occurrences of item in the string
ljust	astring.ljust(w)	Returns a string left-justified in a field of size w
lower	astring.lower()	Returns a string in all lowercase
rjust	astring.rjust(w)	Returns a string right-justified in a field of size w
find	astring.find(item)	Returns the index of the first occurrence of item
split	astring.split(schar)	Splits a string into substrings at schar

Table 5: Operations on a Set in Python

Operation Name	Operator	Explanation
membership	in	Set membership
length	len	Returns the cardinality of the set
|	aset | otherset	Returns a new set with all elements from both sets
&	aset & otherset	Returns a new set with only those elements common to both sets
-	aset - otherset	Returns a new set with all items from the first set not in second
<=	aset <= otherset	Asks whether all elements of the first set are in the second

Table 6: Methods Provided by Sets in Python

Method Name	Use	Explanation
union	aset.union(otherset)	Returns a new set with all elements from both sets
intersection	aset.intersection(otherset)	Returns a new set with only those elements common to both sets
difference	aset.difference(otherset)	Returns a new set with all items from first set not in second
issubset	aset.issubset(otherset)	Asks whether all elements of one set are in the other
add	aset.add(item)	Adds item to the set
remove	aset.remove(item)	Removes item from the set
pop	aset.pop()	Removes an arbitrary element from the set
clear	aset.clear()	Removes all elements from the set

Table 7: Operators Provided by Dictionaries in Python

Operator	Use	Explanation
[]	myDict[k]	Returns the value associated with k, otherwise its an error
in	key in adict	Returns True if key is in the dictionary, False otherwise
del	del adict[key]	Removes the entry from the dictionary

Table 8: Methods Provided by Dictionaries in Python

Method Name	Use	Explanation
keys	adict.keys()	Returns the keys of the dictionary in a dict_keys object
values	adict.values()	Returns the values of the dictionary in a dict_values object
items	adict.items()	Returns the key-value pairs in a dict_items object
get	adict.get(k)	Returns the value associated with k, None otherwise
get	adict.get(k,alt)	Returns the value associated with k, alt otherwise

Table 10: Additional formatting options

Modifier	Example	Description
number	%20d	Put the value in a field width of 20
-	%-20d	Put the value in a field 20 characters wide, left-justified
+	%+20d	Put the value in a field 20 characters wide, right-justified
0	%020d	Put the value in a field 20 characters wide, fill in with leading zeros.
.	%20.2f	Put the value in a field 20 characters wide with 2 characters to the right of the decimal point.
(name)	%(name)d	Get the value from the supplied dictionary using name as the key.

          

>>> price = 24
>>> item = "banana"
>>> print("The %s costs %d cents"%(item,price))
The banana costs 24 cents
>>> print("The %+10s costs %5.2f cents"%(item,price))
The     banana costs 24.00 cents
>>> print("The %+10s costs %10.2f cents"%(item,price))
The     banana costs      24.00 cents
>>> itemdict = {"item":"banana","cost":24}
>>> print("The %(item)s costs %(cost)7.1f cents"%itemdict)
The banana costs    24.0 cents
>>>