How do you format a dictionary python?
1.12.1. Definition and Use of Dictionaries¶In common usage, a dictionary is a collection of words matched with their definitions. Given a word, you can look up its definition. Python has a built in dictionary type called dict which you can use to create dictionaries with arbitrary definitions for character strings. It can be used for the common usage, as in a simple English-Spanish dictionary. Show
Look at the example program """A tiny English to Spanish dictionary is created, using the Python dictionary type dict. Then the dictionary is used, briefly. """ spanish = dict() spanish['hello'] = 'hola' spanish['yes'] = 'si' spanish['one'] = 'uno' spanish['two'] = 'dos' spanish['three'] = 'tres' spanish['red'] = 'rojo' spanish['black'] = 'negro' spanish['green'] = 'verde' spanish['blue'] = 'azul' print(spanish['two']) print(spanish['red']) First an empty dictionary is created using To refer to the definition for a word, you use the dictionary name, follow it by the word inside square brackets. This notation can either be used on the left-hand side of an assignment to make (or remake) a definition, or it can be used in an expression (as in the print functions), where its earlier definition is retrieved. For example, spanish['hello'] = 'hola' makes an entry in our retrieves the definition for Since the Spanish dictionary is defined at the top-level, the variable name Creating the dictionary is a well defined and quite different activity from the use of the dictionary at the end of the code, so we can use a functions to encapsulate the task of creating the dictionary, as in the example program """A tiny English to Spanish dictionary is created, using the Python dictionary type dict. Then the dictionary is used, briefly. """ def createDictionary(): '''Returns a tiny Spanish dictionary''' spanish = dict() spanish['hello'] = 'hola' spanish['yes'] = 'si' spanish['one'] = 'uno' spanish['two'] = 'dos' spanish['three'] = 'tres' spanish['red'] = 'rojo' spanish['black'] = 'negro' spanish['green'] = 'verde' spanish['blue'] = 'azul' return spanish def main(): dictionary = createDictionary() print(dictionary['two']) print(dictionary['red']) main() This code illustrates several things about functions.
We could also use the dictionary more extensively. The example program def main(): dictionary = createDictionary() print('Count in Spanish: ' + dictionary['one'] + ', ' + dictionary['two'] + ', ' +dictionary['three'] + ', ...') print('Spanish colors: ' + dictionary['red'] + ', ' + dictionary['blue'] + ', ' +dictionary['green'] + ', ...') Try it, and check that it makes sense. Python dictionaries are actually more general than the common use of dictionaries. They do not have to associate words and their string definitions. They can associate many types of objects with some arbitrary object. The more general Python terminology for word and definition are key and value. Given a key, you can look up the corresponding value. The only restriction on the key is that it be an immutable type. This means that a value of the key’s type cannot be changed internally after it is initially created. Strings and numbers are immutable. A dictionary is mutable: its value can be changed internally. (You can add new definitions to it!) We will see more mutable and immutable types later and explore more of the internal workings of data types. 1.12.1.1. Number Dictionary Exercise¶Write a tiny Python program (This dictionary illustrates simply that the values in a Python dictionary are not required to be strings.) 1.12.2. Dictionaries and String Formatting¶At the end of the main function in numberFormat = 'Count in Spanish: {one}, {two}, {three}, ...' withSubstitutions = numberFormat.format(one='uno', two='dos', three='tres') print(withSubstitutions) There are several new ideas here!. We are using an alternate form of format string and format method parameters from those described in String Format Operation. Note the form of the string assigned the name As in String Format Operation, the second line uses method calling syntax. A reminder of the syntax for methods:
has the object followed by a period followed by the method name, and further parameters in parentheses. In the example above, the object is the string called When the string
Now we go one
step further: The keyword parameters associate the keyword names with the values after the equal signs. The dictionary from numberFormat.format(one='uno', two='dos', three='tres') returns the same string as numberFormat.format(**dictionary) The special syntax ** before the dictionary indicates that the dictionary is not to be treated as a single actual parameter. Instead keyword arguments for all the entries in the dictionary effectively appear in its place. Below is a substitute for the main method in def main(): dictionary = createDictionary() numberFormat = "Count in Spanish: {one}, {two}, {three}, ..." withSubstitutions = numberFormat.format(**dictionary) print(withSubstitutions) print("Spanish colors: {red}, {blue}, {green}, ...".format(**dictionary)) In this In general, use this syntax for the string format method with a dictionary, returning a new formatted string:
where the format string contains dictionary keys in braces where you want the dictionary values substituted. The dictionary key names must follow the rules for legal identifiers. At
this point we have discussed in some detail everything that went into the first sample program, Look at We will use 1.12.2.1. Mad Lib Exercise¶To confirm your better understanding of 1.12.3. Dictionaries and Python Variables¶Dictionaries are central to the implementation of Python. Each variable identifier is associated with a particular value. These relationships are stored in dictionaries in Python, and these dictionaries are accessible to the user: You can use
the function call For example, run the example program '''Fancier format string example, with locals().''' x = 20 y = 30 sum = x + y prod = x * y formatStr = '{x} + {y} = {sum}; {x} * {y} = {prod}.' equations = formatStr.format(**locals()) print(equations) Note the variable names inside braces in A string like The example program '''Hello to you! Illustrates locals() for formating in print. ''' person = input('Enter your name: ') greeting = 'Hello, {person}!'.format(**locals()) print(greeting) F-Strings: (Optional, but handy!) A simplification for formatting added in Python 3.6 is f-strings. They have many features, but the simplest thing is to shorten formatting of a literal string with local variable references like above: Merely add an '''Fancier f-string example for formatting''' x = 20 y = 30 sum = x + y prod = x * y print(f'{x} + {y} = {sum}; {x} * {y} = {prod}.') # see the f directly before the literal format string # automatically substituting local variable values 1.12.3.1. Quotient String Dictionary Exercise¶Create What does %d and %s do in Python?%d operator
Uses decimal conversion via int() before formatting. %s can accept numeric values also and it automatically does the type conversion.
What will the format () function return?The format() function returns a formatted representation of a given value specified by the format specifier.
What does a dictionary look like in Python?A dictionary is an unordered and mutable Python container that stores mappings of unique keys to values. Dictionaries are written with curly brackets ({}), including key-value pairs separated by commas (,). A colon (:) separates each key from its value.
Can you modify dictionary in Python?Python allows a dictionary object to be mutable, meaning update or add operations are permissible. A new item can be pushed or an existing item can be modified with the aid of an assignment operator. If an element is added to a key that already exists, its value will be changed to the newly added value.
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