Python add to list if unique

Python Add To List If Unique

for number in unique_numbers: list_of_unique_numbers.append(number) On each iteration I add the current number to the list, list_of_unique_numbers. Finally, I return this list at the end of the program. There’s a shorter way to use a set and list to get unique values in Python. That’s what we’ll tackle next. A Shorter Approach with Set

numbers = [1, 1, 2, 3, 3, 4] unique_numbers = [1, 2, 3, 4] numbers = [1, 2, 2, 3, 3, 4, 5] def get_unique_numbers(numbers): list_of_unique_numbers = [] unique_numbers = set(numbers) for number in unique_numbers: list_of_unique_numbers.append(number) return list_of_unique_numbers print(get_unique_numbers(numbers)) # result: [1, 2, 3, 4, 5] unique_numbers = set(numbers) for number in unique_numbers: list_of_unique_numbers.append(number) numbers = [1, 2, 2, 3, 3, 4, 5] unique_numbers = list(set(numbers)) print(unique_numbers) # Result: [1, 2, 3, 4, 5] unique_numbers = list(set(numbers)) numbers = [20, 20, 30, 30, 40] def get_unique_numbers(numbers): unique = [] for number in numbers: if number in unique: continue else: unique.append(number) return unique print(get_unique_numbers(numbers)) # Result: [20, 30, 40] for number in numbers: if number in unique: continue else: unique.append(number) numbers = [20, 20, 30, 30, 40] def get_unique_numbers(numbers): unique = [] for number in numbers: if number not in unique: unique.append(number) return unique #Result: [20, 30, 40] if number not in unique: unique.append(number)

Python list comprehension: adding unique elements into list?

I’m trying to write simpler code for adding unique elements into a python list. I have a dataset that contains a list of dictionaries, and I’m trying to iterate through a list inside the dictionary. Why doesn’t this work? It’s adding all the items, including the duplicates, instead of adding unique items.

unique_items = [] unique_items = [item for d in data for item in d['items'] if item not in unique_items] unique_items = [] for d in data: for item in d['items']: if (item not in unique_items): unique_items.append(item) [<"items":["apple", "banana"]>, <"items":["banana", "strawberry"]>, <"items":["blueberry", "kiwi", "apple"]>] data = [1, 2, 3, 4, 5, 6, 1, 2, 3, 4, 1, 2, 3, 4,] items = [] _ = [items.append(d) for d in data if d not in items] print(items) [1, 2, 3, 4, 5, 6] >>> data = , 2: > >>> >>> >>> list(repeat above) >>> [1, 2, 3, 4, 5] from collections import OrderedDict from itertools import chain l = [<"items":["apple", "banana"]>, <"items":["banana", "strawberry"]>, <"items":["blueberry", "kiwi", "apple"]>] OrderedDict.fromkeys(chain.from_iterable(d['items'] for d in l)).keys() # ['apple', 'banana', 'strawberry', 'blueberry', 'kiwi']

Python | Get unique values from a list

Method 3 : Using numpy.unique. Using Python’s import numpy, the unique elements in the array are also obtained. In first step convert the list to x=numpy.array (list) and then use numpy.unique (x) function to get the unique values from the list. numpy.unique () returns only the unique values in the list. Python3.

Input : 10 20 10 30 40 40 Output : 10 20 30 40 Input : 1 2 1 1 3 4 3 3 5 Output : 1 2 3 4 5 the unique values from 1st list is 10 20 30 40 the unique values from 2nd list is 1 2 3 4 5 the unique values from 1st list is 40 10 20 30 the unique values from 2nd list is 1 2 3 4 5 the unique values from 1st list is [10 20 30 40] the unique values from 2nd list is [1 2 3 4 5] the unique values from 1st list is 10 20 30 40 the unique values from 2nd list is 1 2 3 4 5

Python add unique to list

Get code examples like»python add unique to list». Write more code and save time using our ready-made code examples. Search snippets; Browse Code Answers; FAQ; Usage docs; Log In Sign Up. Home; Python; python add unique to list; user21820. Programming language:Python. 2021-03-27 21:25:42. 0. Q:

myList = ['Arise', 'But', 'It', 'Juliet', 'Who', 'already', 'and', 'and', 'and', 'breaks', 'east', 'envious', 'fair', 'grief', 'is', 'is', 'is', 'kill', 'light', 'moon', 'pale', 'sick', 'soft', 'sun', 'sun', 'the', 'the', 'the', 'through', 'what', 'window', 'with', 'yonder'] auxiliaryList = [] for word in myList: if word not in auxiliaryList: auxiliaryList.append(word)

Assign value to unique number in list in Python

Assign range of elements to List in Python; Python Program to assign each list element value equal to its magnitude order; Largest Unique Number in Python; Program to find the number of unique integers in a sorted list in Python; Unique Number of Occurrences in Python; Count unique sublists within list in Python; List assign() function in C++ STL

# Given List Alist = [5,3,3,12] print("The given list : ",Alist) # Assigning ids to values enum_dict = list_ids = [enum_dict[n] for n in Alist] # Print ids of the dictionary print("The list of unique ids is: ",list_ids) The given list : [5, 3, 3, 12] The list of unique ids is: [2, 0, 0, 1] from itertools import count # Given List Alist = [5,3,3,12] print("The given list : ",Alist) # Assign unique value to list elements dict_ids = list(map(<>.setdefault, Alist, count())) # The result print("The list of unique ids is: ",dict_ids) The given list : [5, 3, 3, 12] The list of unique ids is: [0, 1, 1, 3]

Python | Check if list contains all unique elements

The original list is : [1, 3, 4, 6, 7] List contains all unique elements. Method #2 : Using len () + set () This is most elegant way in which this problem can be solved by using just a single line. This solution converts the list to set and then tests with original list if contains similar no. of elements.

The original list is : [1, 3, 4, 6, 7] List contains all unique elements The original list is : [1, 3, 4, 6, 7] List contains all unique elements The original list is : [1, 3, 4, 6, 7] List contains all unique elements

Python List.append() – How to Append to a List in Python

The append method receives one argument, which is the value you want to append to the end of the list. Here’s how to use this method: mixed = [10, «python», False] mixed.append (40) print (mixed) # [10, ‘python’, False, 40] Using the append method, you have added 40 to the end of the mixed list. You can add any data type you want, including

age = 50 name = "Python" isRunning = False item1 = "banana" item2 = "apple" item3 = "orange" numbers = [1, 2, 3] strings = ["list", "dillion", "python"] mixed = [10, "python", False, [40, "yellow"]] items = ["banana", "apple", "orange"] print(items[0], items[1], items[2]) # banana apple orange mixed = [10, "python", False] mixed.append(40) print(mixed) # [10, 'python', False, 40] mixed = [10, "python", False] mixed.append([True, "hello"]) print(mixed) # [10, 'python', False, [True, 'hello']]

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Add only unique values to a list in python

To eliminate duplicates from a list, you can maintain an auxiliary list and check against.

myList = ['Arise', 'But', 'It', 'Juliet', 'Who', 'already', 'and', 'and', 'and', 'breaks', 'east', 'envious', 'fair', 'grief', 'is', 'is', 'is', 'kill', 'light', 'moon', 'pale', 'sick', 'soft', 'sun', 'sun', 'the', 'the', 'the', 'through', 'what', 'window', 'with', 'yonder'] auxiliaryList = [] for word in myList: if word not in auxiliaryList: auxiliaryList.append(word) 

['Arise', 'But', 'It', 'Juliet', 'Who', 'already', 'and', 'breaks', 'east', 'envious', 'fair', 'grief', 'is', 'kill', 'light', 'moon', 'pale', 'sick', 'soft', 'sun', 'the', 'through', 'what', 'window', 'with', 'yonder'] 

This is very simple to comprehend and code is self explanatory. However, code simplicity comes on the expense of code efficiency as linear scans over a growing list makes a linear algorithm degrade to quadratic.

If the order is not important, you could use set()

A set object is an unordered collection of distinct hashable objects.

Hashability makes an object usable as a dictionary key and a set member, because these data structures use the hash value internally.

Since the average case for membership checking in a hash-table is O(1), using a set is more efficient.

auxiliaryList = list(set(myList)) 

['and', 'envious', 'already', 'fair', 'is', 'through', 'pale', 'yonder', 'what', 'sun', 'Who', 'But', 'moon', 'window', 'sick', 'east', 'breaks', 'grief', 'with', 'light', 'It', 'Arise', 'kill', 'the', 'soft', 'Juliet'] 

Solution 2

Instead of is not operator, you should use not in operator to check whether the item is in the list:

BTW, using set is a lot efficient (See Time complexity):

with open('romeo.txt') as fhand: output = set() for line in fhand: words = line.split() output.update(words) 

UPDATE The set does not preserve the original order. To preserve the order, use the set as an auxiliary data structure:

output = [] seen = set() with open('romeo.txt') as fhand: for line in fhand: words = line.split() for word in words: if word not in seen: # faster than `word not in output` seen.add(word) output.append(word) 

Solution 3

One method is to see if it’s in the list prior to adding, which is what Tony’s answer does. If you want to delete duplicate values after the list has been created, you can use set() to convert the existing list into a set of unique values, and then use list() to convert it into a list again. All in just one line:

If you want to sort alphabetically, just add a sorted() to the above. Here’s the result:

[‘Arise’, ‘But’, ‘It’, ‘Juliet’, ‘Who’, ‘already’, ‘and’, ‘breaks’, ‘east’, ‘envious’, ‘fair’, ‘grief’, ‘is’, ‘kill’, ‘light’, ‘moon’, ‘pale’, ‘sick’, ‘soft’, ‘sun’, ‘the’, ‘through’, ‘what’, ‘window’, ‘with’, ‘yonder’]

Solution 4

Here’s a «one-liner» which uses this implementation of removing duplicates while preserving order:

def unique(seq): seen = set() seen_add = seen.add return [x for x in seq if not (x in seen or seen_add(x))] output = unique([word for line in fhand for word in line.split()]) 

The last line flattens fhand into a list of words, and then calls unique() on the resulting list.

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Получение уникальных значений из списка в Python

В этой статье мы рассмотрим 3 способа получения уникальных значений из списка в Python. Имея дело с огромным количеством необработанных данных, мы часто сталкиваемся с ситуациями, когда нам нужно извлечь уникальный и неповторяющийся набор данных из необработанного набора входных данных.

Для получения уникальных значений из списка в Python можно использовать любой из следующих способов:

• Метод set();
• Использование метода list.append() вместе с циклом for;
• Использование метода Python numpy.unique().

Set() для получения уникальных значений из списка

Set хранит в себе одну копию повторяющихся значений. Это свойство можно использовать для получения уникальных значений из списка в Python.

• Когда список преобразуется в набор, в него помещается только одна копия всех повторяющихся элементов.
• Затем нам нужно будет преобразовать набор обратно в список, используя следующую команду:

list_inp = [100, 75, 100, 20, 75, 12, 75, 25] set_res = set(list_inp) print("The unique elements of the input list using set():\n") list_res = (list(set_res)) for item in list_res: print(item)

The unique elements of the input list using set(): 25 75 100 20 12

list.append() и цикл for

Чтобы найти уникальные элементы, мы можем применить цикл Python for вместе с функцией list.append(), чтобы добиться того же:

• Сначала мы создаем новый (пустой) список, т.е. res_list.
• После этого, используя цикл for, мы проверяем наличие определенного элемента в новом созданном списке (res_list). Если элемент отсутствует, он добавляется в новый список с помощью метода append().

В случае, если при обходе мы сталкиваемся с элементом, который уже существует в новом списке, то есть повторяющимся элементом, в этом случае он игнорируется циклом for. Мы будем использовать оператор if, чтобы проверить, является ли этот элемент уникальным или повторяющимся.

list_inp = [100, 75, 100, 20, 75, 12, 75, 25] res_list = [] for item in list_inp: if item not in res_list: res_list.append(item) print("Unique elements of the list using append():\n") for item in res_list: print(item)

Unique elements of the list using append(): 100 75 20 12 25

numpy.unique() для создания списка с уникальными элементами

Модуль NumPy имеет встроенную функцию с именем numpy.unique для извлечения уникальных элементов данных из массива numpy.

Чтобы получить уникальные элементы из списка Python, нам нужно будет преобразовать список в массив NumPy, используя следующую команду.

Затем мы будем использовать метод numpy.unique() для извлечения уникальных элементов данных из массива numpy и, наконец, распечатаем получившийся список.

numpy.unique(numpy-array-name)

import numpy as N list_inp = [100, 75, 100, 20, 75, 12, 75, 25] res = N.array(list_inp) unique_res = N.unique(res) print("Unique elements of the list using numpy.unique():\n") print(unique_res)

Unique elements of the list using numpy.unique(): [12 20 25 75 100]

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