Master Python’s Core Data Structures: Strings, Lists, Tuples, Dictionaries & Sets

1. Strings

Python strings provide many built‑in methods for manipulation, such as capitalizing, counting characters, centering, checking suffixes, testing digit content, joining, stripping, splitting, and more.

name = 'derek'
print(name.capitalize())          # Derek
print(name.count("e"))           # 2
print(name.center(10, '*'))       # ***derek***
print(name.endswith('k'))         # False
print('244'.isdigit())           # True
print('+'.join(['1','2','3']))    # 1+2+3
print('
123'.strip())           # 123
print('1+2+3+4'.split('+'))      # ['1', '2', '3', '4']

String formatting can be done with format:

msg = 'my name is {name} and i am {age} old'
print(msg.format(name='derek', age=20))
# Output: my name is derek and i am 20 old

Common built‑in methods include:

string.capitalize()          # first character uppercase
string.center(width)        # center with spaces
string.count(sub, beg=0, end=len(string))
string.decode(encoding='UTF-8', errors='strict')
string.encode(encoding='UTF-8', errors='strict')
string.endswith(suffix, beg=0, end=len(string))
string.expandtabs(tabsize=8)
string.find(sub, beg=0, end=len(string))
string.index(sub, beg=0, end=len(string))
string.isalnum()
string.isalpha()
string.isdecimal()
string.isdigit()
string.islower()
string.isnumeric()
string.isspace()
string.istitle()
string.isupper()
string.join(seq)
string.ljust(width)
string.lower()
string.lstrip()
string.maketrans(intab, outtab)
string.max()
string.min()
string.partition(sep)
string.replace(old, new, num=string.count(old))
string.rfind(sub, beg=0, end=len(string))
string.rindex(sub, beg=0, end=len(string))
string.rjust(width)
string.rpartition(sep)
string.rstrip()
string.split(sep="", num=string.count(sep))
string.splitlines(num=string.count('
'))
string.startswith(prefix, beg=0, end=len(string))
string.strip([chars])
string.swapcase()
string.title()
string.translate(table, del="")
string.upper()

2. Lists

Lists are mutable sequences that support indexing, slicing, and a rich set of methods for modification.

# Create a list
fruit = ['apple', 'pear', 'grape', 'orange']

# Indexing and slicing
print(fruit[1])        # pear
print(fruit[1:3])      # ['pear', 'grape']
print(fruit[-1])       # orange
print(fruit[:2])       # ['apple', 'pear']

# Append and remove
fruit.append('peach')
print(fruit)           # ['apple', 'pear', 'grape', 'orange', 'peach']
fruit.remove('peach')
print(fruit)           # ['apple', 'pear', 'grape', 'orange']

# Pop and delete by index
fruit.pop()            # removes 'orange'
print(fruit)           # ['apple', 'pear', 'grape']
del fruit[2]
print(fruit)           # ['apple', 'pear']

# Insert and modify
fruit.insert(1, 'grape')
print(fruit)           # ['apple', 'grape', 'pear']
fruit[2] = 'orange'
print(fruit)           # ['apple', 'grape', 'orange']

# Extend, count, sort, reverse, index
fruit1 = ['apple', 'orange']
fruit2 = ['pear', 'grape']
fruit1.extend(fruit2)
print(fruit1)          # ['apple', 'orange', 'pear', 'grape']
print(fruit1.count('apple'))  # 1
fruit1.sort()
print(fruit1)          # ['apple', 'grape', 'orange', 'pear']
fruit1.reverse()
print(fruit1)          # ['pear', 'orange', 'grape', 'apple']
print(fruit1.index('apple'))   # 3

# Enumerate
for idx, item in enumerate(fruit1):
    print(idx, item)
# 0 pear
# 1 orange
# 2 grape
# 3 apple

3. Tuples

Tuples are immutable sequences.

# Create a tuple
fruit = ('apple', 'orange', 'grape')
print(fruit.count('apple'))   # 1
print(fruit.index('orange'))  # 1

4. Dictionaries

Dictionaries map keys to values and support dynamic insertion, modification, and deletion.

# Create a dictionary
fruit = {1: 'apple', 2: 'orange', 3: 'grape'}
print(fruit)

# Add a new key
fruit[4] = 'pear'
print(fruit)

# Modify a value
fruit[4] = 'peach'
print(fruit)

# Delete a key
fruit.pop(4)
print(fruit)

# Retrieve a value safely
print(fruit.get(1))   # apple

# Iterate over items, keys, values
for k, v in fruit.items():
    print(k, v)
for k in fruit.keys():
    print(k)
for v in fruit.values():
    print(v)

5. Sets

Sets store unordered unique elements and support mathematical operations.

# Create a set
fruit = set(['apple', 'orange', 'pear'])
print(fruit)   # {'orange', 'pear', 'apple'}

# Add single element and multiple elements
fruit.add('grape')
fruit.update(['peach', 'banana'])
print(fruit)

# Remove elements
fruit.remove('banana')
fruit.pop()   # removes an arbitrary element
print(fruit)

# Set operations
num1 = set([11, 22, 33, 44])
num2 = set([33, 44, 55, 66])
print(num1.union(num2))        # {66, 11, 22, 33, 44, 55}
print(num1.difference(num2))   # {11, 22}
print(num1.intersection(num2)) # {33, 44}