Here, we will explain "data structure" for Python beginners. It is supposed to use Python3 series.
list_1.py
list_int = [1, 2, 3, 4, 5] #A list of all numbers
print(list_int)
list_str = ['Python', 'R', 'Java', 'Ruby', 'PHP'] #A list of all strings
print(list_str)
list_bool = [True, False, True, True, False] #List of all Boolean values
print(list_bool)
list_mix = [1, 2, 3, 4, 'GO'] #You can also mix elements of multiple data types in a single list.
print(list_mix)
list_2d = [[1, 2], [3, 4]] #You can also create a list of two or more dimensions.
print(list_2d)
list_empty = [] #Create an empty list.
print(list_empty)
If you want to store consecutive numbers in a list, you can also write as follows.
list_2.py
list_range = list(range(1, 100)) # range(m, n)Is from m to n-It points to a continuous integer of 1 and is converted to a list type.
print(list_range)
list_range_odd = list(range(1, 100, 2)) #You can do it even if it is not in 1 increments.
print(list_range_odd)
list_3.py
list_int = [1, 2, 3, 4, 5]
list_int_1 = list_int[1] #Refer to the value of the element at index 1 (second).
print(list_int_1)
list_int_0 = list_int[0] #Refer to the value of the element at index 0 (1st).
print(list_int_0)
list_int_minus1 = list_int[-1] #Refer to the value of the first element counting from the back.
print(list_int_minus1)
list_2d = [[1, 2], [3, 4]]
list_2d_0 = list_2d[0]
print(list_2d_0) #Refer to the value of the element at index 0 (1st).
list_2d_0_0 = list_2d[0][0]
print(list_2d_0_0) #Refer to the value of the element of index 0 (1st) in index 0 (1st).
#If you specify an index value that does not contain an element, an error will occur.
list_int_12 = list_int[12]
print(list_int_12)
list_int_slice1to3 = list_int[1:3] #Slice (take out elements of a specific section continuously)
print(list_int_slice1to3)
You can treat strings like a list (you can refer to the Xth character from the front, etc.).
list_4.py
var_str = 'abcde'
print(var_str[3])
print(var_str[1:3])
list_5.py
list_int = [1, 2, 3, 4, 5]
list_int[2] = 6 #Update the value at index 2.
print(list_int)
You can use the in operator to determine if a value is included as an element of the list (returns True if it is included, False if it is not).
list_6.py
list_int = [1, 2, 3, 4, 5]
print(2 in list_int) #True is output
print(12 in list_int) #False is output
You can use len () to get the number of elements in the list.
list_7.py
list_int = [1, 2, 3, 4, 5]
list_int_length = len(list_int)
print(list_int_length)
You can use it for strings as follows (you can count the number of characters).
list_8.py
var_str = 'abcde'
var_str_length = len(var_str)
print(var_str_length)
list_9.py
ones = [1] * 5 #Repeat the same list a specified number of times.
print(ones)
rep = [1, 2, 3] * 4
print(rep)
nums_1 = [1, 2, 3]
nums_2 = [4, 5]
nums_3 = nums_1 + nums_2 #Combine lists.
print(nums_3)
list_10.py
nums = [1, 2, 3, 4, 5]
nums.append(6) #Add an element to the end of the list.
print(nums)
nums.extend([7, 8, 9]) #Add all iterable elements to the end of the list.
print(nums)
nums.insert(5, 10) #Add element 10 before the fifth element in the index.
print(nums)
nums.remove(10) #Delete element 10.
print(nums)
print(nums.pop(1)) #Deletes the first element of the index and returns it.
print(nums.pop()) #If the index number is not specified, the last element is deleted and returned.
print(nums.index(5)) #Finds the specified element and returns its position.
print(nums.count(3)) #Returns the number of occurrences of the specified element.
nums.sort(key=None, reverse=False) #Sort the list. You can specify the comparison function with key. reverse=If True, sort in descending order.
print(nums)
nums.reverse() #Reverse order with in-place operation.
print(nums)
nums_rev = nums[::-1] #Reverse the order.
print(nums_rev)
nums_copy = nums.copy() #Make a copy.
print(nums_copy)
del nums[6] #Deletes the element with the specified index number.
print(nums)
nums.clear() #Delete all elements of the list.
print(nums)
tupple_1.py
tupple_int = (1, 2, 3, 4, 5)
print(tupple_int)
tupple_2.py
tupple_int_1 = tupple_int[1] #See the value of the element at index 1 (2nd)
print(tupple_int_1)
tupple_int_0 = tupple_int[0] #See the value of the element at index 0 (1st)
print(tupple_int_0)
tupple_single = (1,) #Tuple with 1 element
print(tupple_single)
Tuple values cannot be updated (this is a big difference from the list). Conversely, tuples are a good way to convert values that you don't want to update in the middle of processing into an array format.
tupple_3.py
tupple_int = (1, 2, 3, 4, 5)
tupple[2] = 6 #An error will occur.
dictionary_1.py
dict_human = {'height': 200, 'body weight': 100, 'BMI': 25} # {key: value}Create in the form of.
print(dict_human)
dict_empty = {} #Create an empty dictionary.
print(dict_empty)
dictionary_2.py
dict_human = {'height': 200, 'body weight': 100, 'BMI': 25}
dict_human_height = dict_human['height']
print(dict_human_height)
dictionary_3.py
dict_human = {'height': 200, 'body weight': 100, 'BMI': 25}
dict_human['height'] = 180
print(dict_human)
If you specify a key that is not in the dictionary and assign a value, a new key will be added.
dictionary_4.py
dict_human = {'height': 200, 'body weight': 100, 'BMI': 25}
dict_human['sex'] = 'Man'
print(dict_human)
dictionary_5.py
dict_human = {'height': 200, 'body weight': 100, 'BMI': 25}
print(dict_human.keys()) #Returns a list of keys that exist in the dictionary.
print(dict_human.values()) #Returns a list of values that exist in the dictionary.
print(dict_human.items()) #Returns a list of key / value combinations that exist in the dictionary.
print(dict_human.get('height', 'unknown')) #If there is a key specified by the first argument, its value is returned.
print(dict_human.get('blood type', 'unknown')) #If the key specified by the first argument does not exist, the value specified by the second argument is returned.
dict_human_pop = dict_human.pop('BMI') #Deletes the specified key and returns it.
print(dict_human_pop) #Returns the value of the deleted key.
print(dict_human) #Returns the deleted dictionary.
del dict_human['body weight'] #Delete the specified key.
print(dict_human)
dict_human.clear() #Delete all elements of the dictionary.
print(dict_human)
set_1.py
set_int = {1, 2, 3, 4, 5}
print(set_int)
set_empty = set()
print(set_empty)
set_2.py
set_int = {1, 2, 3, 4, 5}
set_int.add(6) #Add items in parentheses.
print(set_int)
set_int.update([7, 8, 9, 10]) #Add all the iterable elements in parentheses.
print(set_int)
set_int.pop() #Deletes one of the elements and returns it.
print(set_int)
set_int.remove(10) #Delete the item in parentheses. An error will occur if the specified item does not exist.
print(set_int)
set_int.discard(10) #Delete the item in parentheses. No error occurs even if the specified item does not exist.
print(set_int)
set_int_2 = {1, 2, 3}
print(set_int.isdisjoint(set_int_2)) # set_int_True is returned if there is no element in common with 2.
print(set_int.issubset(set_int_2)) # set_int_If it is a subset of 2, True is returned.
print(set_int.issuperset(set_int_2)) # set_int_If 2 is a subset, True is returned.
print(set_int.difference(set_int_2)) # set_int_Returns the set (difference set) with the elements of 2 removed.
set_int.difference_update(set_int_2) # set_int_Replace with the set of differences from 2.
print(set_int)
print(set_int.intersection(set_int_2)) # set_int_Returns the intersection (product set) with 2.
set_int.intersection_update(set_int_2) # set_int_Replace with an intersection with 2.
print(set_int)
print(set_int.symmetric_difference(set_int_2)) #Returns a set of elements (symmetric difference) contained in only one.
set_int.symmetric_difference_update(set_int_2) # set_int_Replace with symmetric difference with 2.
print(set_int)
print(set_int.union(set_int_2)) # set_int_Returns a set (union) with 2 elements added.
set_int.update(set_int_2) # set_int_Replace with the union with 2.
print(set_int)
set_int_copy = set_int.copy()
print(set_int_copy)
set_int.clear()
print(set_int)
set_3.py
set_1 = {3, 4, 5}
set_2 = {1, 2, 3, 4, 5}
print(set_1 <= set_2) # set_1 is set_Whether it is a subset of 2
print(set_1.issubset(set_2) or set_2.issuperset(set_1))
print(set_1 < set_2) # set_1 is set_Is it a subset of 2 and not the same set?
print(set_1 <= set_2 and set_1 != set_2)
print(set_1 == set_2) # set_1 and ser_Whether 2 is the same set
print(set_1 <= set_2 and set_1 >= set_2)
print(3 in set_1) #Whether the item is included in the set
set_4.py
set_1 = {3, 4, 5}
set_2 = {1, 2, 3, 4, 5}
print(set_1 - set_2) #Difference set
print(set_1.difference(set_2))
print(set_1 & set_2) #Intersection
print(set_1.intersection(set_2))
print(set_1 | set_2) #Union
print(set_1.union(set_2))
print(set_1 ^ set_2) #Symmetric difference
print(set_1.symmetric_difference(set_2))
Here, we have explained "list", "tupple", "dictionary", and "set" as data types in Python. For the time being, I think it would be good if I could understand the "list" and "dictionary".
What is the programming language Python? Can it be used for AI and machine learning?
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