Python's List2DictionaryConverter: Ten Methods

Python listsLists in Python and dictionaries are two types of data structures in Python. Python lists are sequences of objects in order, while dictionaries are collections of objects in random order. The items in the listlist items can be looked up in an index (based on their position) and dictionary entries (unlike index entries) can only be looked up using keys (and not their position).

  It's time to learn how to transform a Python list into a dictionary.

  1. Making a dictionary out of a list of tuples
  2. Making a dictionary from two lists of equal length
  3. Making a dictionary from two lists of varying lengths
  4. Making a dictionary out of a list of alternate key, value pairs
  5. Synthesizing multiple dictionaries into one
  6. Making a dictionary out of a set of items using enumerate()
  7. Making a dictionary from a list through study of dictionaries
  8. Using dictionaries to transform lists dict fromkeys()
  9. An application of dictionary comprehension to the process of converting a nested list into a dictionary
  10. Implementing a DictionaryConverter to transform a list into a dictionary Counter()

One Method for Creating a Dictionary from a Sequence of Tuples

The dict() dictionary is constructed by the constructor from a list of key-value pairs.

#Using the dict() constructor to transform the tuple list into a dictionary color=[('red',1),('blue',2),('green',3)] d=dict(color) 'red' = 1, 'blue = 2,' 'green = 3,' print (d)#Output

Extra Python Stuff: How do you define Python?

Creating a Dictionary from Two Lists of Equal Length

A dictionary can be used to transform two lists of equal length. zip()

zip() gives back an iterator of tuples That zip object can be transformed into a dictionary with the dict() constructor

zip()

Create a new iterator that combines data from all the iterables.

zip(*iterables) Provides a tuple iterator where each element of the sequences or iterables passed in as arguments is contained in the ith tuple. When the iterator reaches the end of the shortest iterable in the input, it exits. This function takes a single iterable argument and produces a stream of one-tuple iterators. It returns a null iterator if no arguments are given, per the Python documentation. documentation

Example

l1=[1,2,3,4] l2=['a','b','c','d'] d1=zip(l1,l2) . print (d1)#Output: Zip object to dict conversion using the dict() constructor. write (dict(d1)) As an example of zip()'s operation, the following output is generated: #Output: 1: 'a', 2: 'b,' 3: 'c,' 4: 'd' Indhumathy Chelliah's Artwork

3.Creating a Dictionary from Two Lists of Varying Length

Using, two lists of varying lengths can be mapped onto the dictionary. itertools zip_longest()

It is believed that Python’s documentationPython's reference manual , “ zip_longest() Produces an iterator that combines items from all of the iterables. If the lengths of the iterables aren't uniform, fillvalue is used to make up the difference. The iteration will proceed until the longest iterable has run out. ”

itertools zip_longest(*iterables,fillvalue=None)

Using zip() This process of iteration will keep going until the shortest iterable is found. feels drained

l1=[1,2,3,4,5,6,7] l2=['a','b','c','d'] d1=zip(l1,l2) display (d1)#Output: Using the dict() constructor to change a zip object into a dictionary. write (dict(d1)) #1 = 'a,' #2 = 'b,' #3 = 'c,' #4 = 'd'

Using zip_longest() repetitions are made until a desired result is reached. the The longest possible iteration has been used up. As a result, fillvalue is None

ZIP_LONGEST is a required import from itertools. l1=[1,2,3,4,5,6,7] l2=['a','b','c','d'] d1=zip_longest(l1,l2) message (d1)#Output: Zip object to dict conversion using the dict() constructor. echo (dict(d1)) As an example of how zip_longest() operates, the following values are returned: (1) "a," (2) "b," (3) "c," (4) "d," (5) "Nothing," (6) "Nothing," and (7) "Nothing." Indhumathy Chelliah's Artwork

fillvalue referenced as x

Bring in zip_longest from itertools. l1=[1,2,3,4,5,6,7] l2=['a','b','c','d'] d1=zip_longest(l1,l2,fillvalue='x') write (d1)#Results: #Using the dict() constructor to transform a zip object into a dictionary In other words, print (dict(d1)). #Output:1: 'a', 2: 'b', 3: 'c', 4: 'd', 5: 'x', 6: 'x', 7: 'x'

Creating a Dictionary from a Set of Alternate Keys and Values

Using slicing, we can transform a list of alternate keys and values into a dictionary.

When you slice an existing list, you get back a new list with the specified subset of items. The indexes can be set within a certain range.

s[i:j:k] denotes a section of s starting at index i and ending at index j via operation k.

We have the option of making two separate slice lists. One list is composed entirely of keys, while the other is made up of values.

l1=[1,'a',2,'b',3,'c',4,'d']

Split this list into two slices.

The primary object of the slices data type will consist only of keys:

l1[::2]

start has not been mentioned In its default state, it will begin at the top of the list.

stop not mentioned In its default setting, it will terminate at the final item in the list.

stop cited as 2

l1[::2] Step two (alternative elements) should return a list with items from start to finish.

[1, 2, 3, 4]An example of how to make a dictionary out of a list of changing values. Photos by Indhumathy Chelliah

The data in the second slice will be made up solely of numeric values.

l1=[1,'a',2,'b',3,'c',4,'d']l1[1::2]

start appears as the number 1 The first index will be the starting point for the slicing action.

stop does not appear When the list is exhausted, it will stop.

step appears to be 2

l1[1::2] Step 2 (alternative elements): Return a list containing the elements from the starting index to the end.

Example of using the zip() function to combine lists with elements ['a,' ['b,' ['c,' ['d]] | Photo by Indhumathy Chelliah

At this point, we can combine the two lists by using the zip() function

l1=[1,'a',2,'b',3,'c',4,'d'] Using a slicing operation, we can generate a new list that consists only of the keys. l2=l1[::2] Values-only list, created by slicing #main list l3=l1[1::2] This is an example of using the zip() function to combine two lists. z=zip(l2,l3) A dict is created from a zip file using the dict() constructor. The output was: print (dict(z)) #1 = 'a,' #2 = 'b,' #3 = 'c,' #4 = 'd'

Reducing Multiple Dictionaries into One

The following methods can be used to combine multiple dictionaries into one:

  • dict update()
  • Knowledge of a Dictionary
  • Collections ChainMap

 

dict update()

Using this method, we can compress multiple dictionaries into one. dict update()

  • Build a dictionary from scratch.
  • Use a for loop to iterate over the dictionary list. for loop
  • Change every entry (key-value pair) to the empty dictionary using dict update()
l1=[{1:'a',2:'b'},{3:'c',4:'d'}] d1={} where i is a letter in l1 d1 update(i) print (d1) #1 = 'a,' #2 = 'b,' #3 = 'c,' #4 = 'd'

Knowledge of the Dictionary

Brackets are the building blocks of dictionary knowledge. {} comprised of two phrases split by a colon and a for statement, then either 0 or 1 for or if clauses

l1=[{1:'a',2:'b'},{3:'c',4:'d'}] For (k,v) in e, the solution is d1=k:v in l1. items()}

in l1 for e: Give back each item in the list. {1:’a’,2:’b’}

e for (k,v) items() Please provide the item's key-value pair. ( 1,'a') (2,'b')

k:v Is now reflected in the D1 dictionary

l1=[{1:'a',2:'b'},{3:'c',4:'d'}] For (k,v) in e, we have d1=k:v in l1. items()} print (d1) #1 = 'a,' #2 = 'b,' #3 = 'c,' #4 = 'd'

Collections ChainMap

By using collections ChainMap() dictionary lists can be merged into one larger dictionary

ChainMap : According to the paper "ChainMap: Grouping Dictionaries and Other Mappings into a Single, Dynamic View," Python’s documentationPython's reference manual

We'll be getting a return type of Object in a ChainMap To create a dictionary, we use the dict() constructor

A primer on the Python list-to-dictionary conversion | Watch the Trinity Software Academy Video

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6. Using Enumerate() to Turn a List Into a Dictionary

By using enumerate() Lists can be turned into dictionaries where the index becomes the key and the item becomes the value.

enumerate() will result in an enumerate object being returned

By utilizing the dict() constructor

count(iterable, start=0) Provides access to the enumerate object. A valid iterable is a sequence or a i tool for performing iterations, also called a terator. The __next__() The iterator's Return Method Has Been Called method enumerate() According to the documentation, "returns a tuple containing a count (from start, which defaults to 0) and the values obtained from iterating over iterable." Python documentationA Reference Manual for Python

l1=['a','b','c','d'] d1=dict(enumerate(l1)) 0 = 'a,' 1 = 'b,' 2 = 'c,' 3 = 'd' print (d1)#Output

Converting a List into a Dictionary through Knowledge of the Dictionary 7.

Dictionary comprehension allows us to take a set of keys and produce a dictionary with the same meaning.

D1=k:"a" for k in l1

In each loop, it will use a different item from the list as a key ( k ) and the worth will be a every possible key

l1=[1,2,3,4] If you replace k with "a" in l1, you get the formula: d1=k:"a." print (d1) First, "a," then "a," then "a," and finally "a."

8. Using dict to transform a list into a dictionary fromkeys()

dict Obtaining Keys from keys() accepts a list of keys, which are transformed into dictionary keys, and an assignable value.

All the keys will be given the same value.

l1=['red','blue','orange'] d1=dict fromkeys(l1,"colors") print (d1) Red = "colors," Blue = "colors," and Orange = "colors" in the #Output.

9. Using Dictionary Knowledge to Convert a Tree-Structured List to a Dictionary

Using dictionary comprehension, we can transform a nesting list into a dictionary.

l1 = [[1,2],[3,4],[5,[6,7]]] Given a vector L1, let d1=x[0]:x[1] for x.

The list will be cycled through repeatedly.

Specifically, it will accept the item at index 0 as the primary key, and index 1 as the value

l1 = [[1,2],[3,4],[5,[6,7]]] In l1, let x be a variable, and let d1=x[0]:x[1]. To output (1, 2, 3, 4, 5), [6, 7], type: print(d1).

Extra Python Stuff: Python: Nested List Comprehensions and Their Construction

Using Counter() to Change a List into a Dictionary

Counter : If you need to keep track of the number of hashable objects, you can use the Counter dict subclass. It's a set where the tally of something is kept as a dictionary value and the tally of other things is kept as a dictionary According to Python's documentation, "counts may take the form of any positive or negative integer." documentation

collections Counter(iterable-or-mapping)

Counter() will make frequencies of list items into values and keys to identify them

Counter is imported from the collections. c1=Counter(['c','b','a','b','c','a','b']) Frequency values are represented by #key, which are the elements themselves. to the console, print (c1)#Output:Counter('b': 3, 'c': 2, 'a': 2) 'c': 2, 'b': 3, 'a': 2,' print (dict(c1))#Output:
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