Dictionaries
Dictionaries
11.9 Glossary
mapping:
A relationship in which each element of one set corresponds to an element of another set.
dictionary:
A mapping from keys to their corresponding values.
key-value pair:
The representation of the mapping from a key to a value.
item:
In a dictionary, another name for a key-value pair.
key:
An object that appears in a dictionary as the first part of a key-value pair.
value:
An object that appears in a dictionary as the second part of a key-value pair. This is more specific than our previous use of the word "value".
implementation:
A way of performing a computation.
hashtable:
The algorithm used to implement Python dictionaries.
hash function:
A function used by a hashtable to compute the location for a key.
hashable:
A type that has a hash function. Immutable types like integers, floats and strings are hashable; mutable types like lists and dictionaries are not.
lookup:
A dictionary operation that takes a key and finds the corresponding value.
reverse lookup:
A dictionary operation that takes a value and finds one or more keys that map to it.
raise statement:
A statement that (deliberately) raises an exception.
singleton:
A list (or other sequence) with a single element.
call graph:
A diagram that shows every frame created during the execution of a program, with an arrow from each caller to each callee.
memo:
A computed value stored to avoid unnecessary future computation.
global variable:
A variable defined outside a function. Global variables can be accessed from any function.
global statement:
A statement that declares a variable name global.
flag:
A boolean variable used to indicate whether a condition is true.
declaration:
A statement like global that tells the interpreter something about a variable.