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How to Remove Duplicate Adjacent Spaces in Python
This Python function collapses any sequence of two or more adjacent spaces into a single space, preserving all other characters.
def remove_duplicate_adjacent_spaces(text):
"""Replace sequences of 2+ spaces with a single space."""
result = []
prev_was_space = False
for char in text:
if char == " ":
if not prev_was_space:
result.append(char)
prev_was_space = True
else:
…Check if List is Sorted Ascending in Python
Verify that a list is sorted in ascending order using the all() function and a generator expression.
def is_sorted_ascending(lst):
return all(lst[i] <= lst[i + 1] for i in range(len(lst) - 1))
if __name__ == "__main__":
test_lists = [
[1, 2, 3, 4, 5],
[1, 3, 2, 4, 5],
[5, 4, 3, 2, 1],
[1, 1, 2, 2, 3],
[10],
[]
]
for lst in test_lists:
print(f"{l…Truncate List Keeping Last N Elements in Python
Return a new list containing only the last N elements from a sequence, handling edge cases like zero or oversized counts.
def truncate(seq, keep_last_n):
"""Return a new list keeping only the last n elements."""
if keep_last_n <= 0:
return []
return list(seq)[-keep_last_n:]
if __name__ == "__main__":
data = [10, 20, 30, 40, 50, 60]
print(truncate(data, 3))
print(truncate(data, 0))
print(truncate(data…Chain Generators with yield from in Python
Combine multiple generators into one seamless sequence using the `yield from` delegation syntax in Python.
def numbers():
yield 1
yield 2
yield 3
def letters():
yield 'a'
yield 'b'
yield 'c'
def combined():
yield from numbers()
yield from letters()
if __name__ == "__main__":
print(list(combined()))How to Create Generator Functions with yield in Python
Create a memory-efficient generator function using yield to produce a Fibonacci sequence up to a limit.
def fibonacci_sequence(limit):
"""Generate Fibonacci numbers up to a given limit."""
a, b = 0, 1
while a <= limit:
yield a
a, b = b, a + b
if __name__ == "__main__":
fib_gen = fibonacci_sequence(100)
for number in fib_gen:
print(number, end=" ")
print()How to Pipe Data Through a List of Transform Functions in Python
Applies a sequence of functions to an initial value using functools.reduce, creating a reusable pipe utility.
from functools import reduce
def pipe(data, *transforms):
return reduce(lambda value, func: func(value), transforms, data)
def double(x):
return x * 2
def add_one(x):
return x + 1
def to_string(x):
return f"Result: {x}"
if __name__ == "__main__":
initial = 5
result = pipe(initial, double, …Find Longest Consecutive Run in an Unsorted List in Python
Find the length of the longest sequence of consecutive integers in an unsorted list using a set and a linear scan.
def longest_run(nums):
if not nums:
return 0
num_set = set(nums)
longest = 0
for num in num_set:
# Only start counting from the smallest number in a sequence
if num - 1 not in num_set:
current = num
length = 1
while current + 1 in num_set:
…Find Median of Two Sorted Arrays in Python
Merges two sorted arrays with a two-pointer walk and returns the median of the combined sorted sequence.
def median_of_two_sorted_arrays(nums1, nums2):
merged = []
i = j = 0
while i < len(nums1) and j < len(nums2):
if nums1[i] <= nums2[j]:
merged.append(nums1[i])
i += 1
else:
merged.append(nums2[j])
j += 1
merged.extend(nums1[i:])
merged.…Find Missing Number in Python Sequence 1 to N
Find the missing number from a list containing numbers 1 to N using the arithmetic sum formula.
def find_missing_number(nums, n):
expected_sum = n * (n + 1) // 2
actual_sum = sum(nums)
return expected_sum - actual_sum
if __name__ == "__main__":
n = 10
numbers = [1, 2, 3, 4, 5, 6, 7, 9, 10]
missing = find_missing_number(numbers, n)
print(f"The missing number is: {missing}")Find the Last Index Where a Condition Is True in Python
This code scans a sequence from the end and returns the index of the last element that satisfies a given condition, or -1 if none do.
def last_index_where(sequence, condition):
"""Return the index of the last element in sequence that satisfies condition."""
for i in range(len(sequence) - 1, -1, -1):
if condition(sequence[i]):
return i
return -1
if __name__ == "__main__":
numbers = [1, 4, 7, 2, 9, 5, 8, 3]
is_…How to Generate Fibonacci Sequence in Python
Generate the first n Fibonacci numbers as a list using a simple iterative loop.
def fibonacci(n):
"""Generate the first n terms of the Fibonacci sequence."""
if n <= 0:
return []
seq = [0, 1]
while len(seq) < n:
seq.append(seq[-1] + seq[-2])
return seq[:n]
if __name__ == "__main__":
n = 10
result = fibonacci(n)
print(result)How to Generate a Geometric Progression List in Python
This Python function builds a list of n terms in a geometric progression, starting with a given first term and multiplying by a constant ratio at each step.
def geometric_progression(first_term, ratio, count):
"""
Generate a list of 'count' terms in a geometric progression
starting with 'first_term' and multiplied by 'ratio' each step.
"""
progression = []
current = first_term
for _ in range(count):
progression.append(current)
c…How to Generate an Arithmetic Progression List in Python
Generates a list of terms in an arithmetic progression using a list comprehension.
def generate_ap(start, difference, count):
"""Generate a list of n terms in an arithmetic progression."""
return [start + i * difference for i in range(count)]
if __name__ == "__main__":
ap = generate_ap(3, 5, 6)
print(ap)How to Sample Random Items Without Replacement in Python
Select k random unique items from a sequence using random.sample for uniform, non-repeating selection.
import random
def sample_without_replacement(population, k):
"""Return k random items from population without replacement."""
if k > len(population):
raise ValueError("k cannot exceed population size")
# Use random.sample for O(k) time, no mutation of the original
return random.sample(populati…Insert an Element Every n Positions in Python
Insert a given element before or after every n-th position in a Python list, returning a new list with the placements applied.
def insert_every_n(seq, element, n, position="after"):
"""Insert an element before or after every n-th position in a list.
Args:
seq: Input list
element: Element to insert
n: Insert every n positions (n > 0)
position: 'before' or 'after' (default: 'after')
Returns:
…Generator Function to Yield an Infinite Counter in Python
This code demonstrates a generator function that yields an infinite sequence of integers starting from a given value, allowing lazy, memory-efficient iteration.
def infinite_counter(start=0):
count = start
while True:
yield count
count += 1
if __name__ == "__main__":
counter = infinite_counter(5)
for _ in range(5):
print(next(counter))How to Build a Sliding Window Generator in Python
Create a generator that yields fixed-size overlapping slices of a sequence, useful for efficient windowed iteration.
def sliding_window(sequence, size):
for i in range(len(sequence) - size + 1):
yield sequence[i:i + size]
if __name__ == "__main__":
data = [1, 2, 3, 4, 5]
n = 3
for window in sliding_window(data, n):
print(window)How to Create an Infinite Arithmetic Sequence Generator in Python
Build a memory-efficient generator that yields an infinite arithmetic progression and extract the first N values with list comprehension.
"""Count generator infinite arithmetic progression"""
def arithmetic_counter(start=0, step=1):
"""Generate an infinite arithmetic sequence."""
current = start
while True:
yield current
current += step
if __name__ == "__main__":
counter = arithmetic_counter(1, 3)
result = [next(c…How to Delegate Iteration to a Subgenerator with yield from in Python
Use yield from to delegate iteration from one generator to a subgenerator, flattening nested generator output into a single sequence.
def subgenerator():
yield "first"
yield "second"
yield "third"
def delegate():
yield "before delegation"
yield from subgenerator()
yield "after delegation"
if __name__ == "__main__":
for item in delegate():
print(item)How to Generate Fibonacci Numbers in Python Without Recursion
Build an efficient infinite Fibonacci sequence using a generator function with O(1) memory and no recursion overhead.
def fib(n):
a, b = 0, 1
for _ in range(n):
yield a
a, b = b, a + b
if __name__ == "__main__":
count = 10
result = list(fib(count))
print(result)How to Generate a Collatz Sequence in Python
Generate the Collatz sequence for a given positive integer by repeatedly applying the 3n+1 rule until reaching 1.
def collatz_sequence(n):
if n <= 0:
raise ValueError("n must be a positive integer")
sequence = [n]
while n != 1:
if n % 2 == 0:
n = n // 2
else:
n = 3 * n + 1
sequence.append(n)
return sequence
if __name__ == "__main__":
start = 7
result…How to Reset Python's Random Seed for Deterministic Output
This code shows how to seed Python's random module to generate identical random sequences across runs, ensuring reproducibility.
import random
def seeded_random_sequence(seed, count=5, low=1, high=100):
random.seed(seed)
return [random.randint(low, high) for _ in range(count)]
if __name__ == "__main__":
seed_value = 42
first_run = seeded_random_sequence(seed_value)
print("First run:", first_run)
# Reset seed and gener…How to Slice a Generator with islice in Python
Use itertools.islice to take the first n items from any iterable without materializing the whole sequence into a list.
from itertools import islice
def first_n(iterable, n):
"""Return the first n items from an iterable."""
return list(islice(iterable, n))
if __name__ == "__main__":
numbers = range(10, 100) # large iterable
result = first_n(numbers, 5)
print(result) # [10, 11, 12, 13, 14]How to skip items until a condition is met in Python
Use itertools.dropwhile to skip leading elements while a predicate returns true, then yield the rest of the sequence unchanged.
def is_negative(x):
return x < 0
numbers = [-3, -1, 0, 5, 2, -8, 7]
result = list(itertools.dropwhile(is_negative, numbers))
print(f"Original: {numbers}")
print(f"After dropwhile: {result}")Browse by section
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