Date and Time

Date Directives

Format Meaning Example
%Y Year (4 digits) 2025
%y Year (2 digits) 25
%m Month (01-12) 07
%B Full month name July
%b Abbreviated month name Jul
%d Day of the month (01–31) 17
%j Day of year (001–366) 198
%A Full weekday name Thursday
%a Abbreviated weekday name Thu
%w Weekday as decimal (0=Sunday) 4
%U Week number (Sunday as first day) 28
%W Week number (Monday as first day) 28

Time Directives

Format Meaning Example
%H Hour (24-hour clock, 00–23) 18
%I Hour (12-hour clock, 01–12) 06
%p AM or PM PM
%M Minute (00–59) 45
%S Second (00–59) 30
%f Microsecond (000000–999999) 123456
%z UTC offset +0530
%Z Time zone name IST

Data Types and Structures

String

Syntax Purpose Example
str.upper() Convert to uppercase "hello".upper() → "HELLO"
str.lower() Convert to lowercase "HELLO".lower() → "hello"
str.title() Convert to title case "hello world".title() → "Hello World"
str.capitalize() Capitalize first letter "hello".capitalize() → "Hello"
str.strip() Remove whitespace from both ends " hello ".strip() → "hello"
str.split(sep) Split string into list "a,b,c".split(",") → ["a", "b", "c"]
str.join(iterable) Join iterable into string ",".join(["a", "b", "c"]) → "a,b,c"
str.replace(old, new) Replace substring "hello world".replace("world", "Python") → "hello Python"
str.find(sub) Find substring index "hello".find("e") → 1
str.count(sub) Count occurrences of substring "hello".count("l") → 2
str.startswith(prefix) Check if string starts with prefix "hello".startswith("he") → True
str.endswith(suffix) Check if string ends with suffix "hello".endswith("lo") → True
str.isdigit() Check if string is a digit "123".isdigit() → True
str.isalpha() Check if string is alphabetic "abc".isalpha() → True
str.isalnum() Check if string is alphanumeric "abc123".isalnum() → True
str.islower() Check if string is lowercase "hello".islower() → True
str.isupper() Check if string is uppercase "HELLO".isupper() → True
str.isprintable() Check if string is printable "hello".isprintable() → True
str.swapcase() Swap case of all characters "Hello World".swapcase() → "hELLO wORLD"
str.zfill(width) Pad string with zeros on the left "42".zfill(5) → "00042"

List

Syntax Purpose Example
list.append(item) Add item to end of list [1, 2].append(3) → [1, 2, 3]
list.extend(iterable) Extend list with iterable [1, 2].extend([3, 4]) → [1, 2, 3, 4]
list.insert(index, item) Insert item at index [1, 2].insert(1, 1.5) → [1, 1.5, 2]
list.remove(item) Remove first occurrence of item [1, 2, 3].remove(2) → [1, 3]
list.pop(index) Remove and return item at index [1, 2, 3].pop(1) → 2
list.clear() Remove all items from list [1, 2, 3].clear() → []
list.index(item) Return index of first occurrence [1, 2, 3].index(2) → 1
list.count(item) Count occurrences of item [1, 2, 3].count(2) → 1
list.sort() Sort list in place [3, 1, 2].sort() → [1, 2, 3]
list.reverse() Reverse list in place [1, 2, 3].reverse() → [3, 2, 1]
list.copy() Return shallow copy of list [1, 2, 3].copy() → [1, 2, 3]
list.index(item, start, end) Return index of item in range [1, 2, 3].index(2, 0, 3) → 1
list.sort(key=None, reverse=False) Sort list with optional key and reverse [3, 1, 2].sort(key=lambda x: -x) → [3, 2, 1]
a_list[0] Access first element of list [1, 2, 3][0] → 1
a_list[-1] Access last element of list [1, 2, 3][-1] → 3
a_list[1:3] Slice list from index 1 to 2 [1, 2, 3][1:3] → [2, 3]
a_list[:2] Slice list from start to index 1 [1, 2, 3][:2] → [1, 2]
a_list[1:] Slice list from index 1 to end [1, 2, 3][1:] → [2, 3]
a_list[::2] Slice list with step 2 [1, 2, 3, 4][::2] → [1, 3]
a_list[::-1] Reverse list [1, 2, 3][::-1] → [3, 2, 1]
a_list * 2 Repeat list [1, 2] * 2 → [1, 2, 1, 2]
a_list + b_list Concatenate lists [1, 2] + [3, 4] → [1, 2, 3, 4]
len(a_list) Get length of list len([1, 2, 3]) → 3

Dictionary

Syntax Purpose Example
dict[key] Access value by key {"a": 1, "b": 2}["a"] → 1
dict[key] = value Set value for key {"a": 1, "b": 2}["c"] = 3 → {"a": 1, "b": 2, "c": 3}
dict.get(key, default) Get value by key with default {"a": 1}.get("b", 0) → 0
dict.keys() Get all keys {"a": 1, "b": 2}.keys() → dict_keys(['a', 'b'])
dict.values() Get all values {"a": 1, "b": 2}.values() → dict_values([1, 2])
dict.items() Get all key-value pairs {"a": 1, "b": 2}.items() → dict_items([('a', 1), ('b', 2)])
dict.pop(key) Remove and return value by key {"a": 1, "b": 2}.pop("a") → 1
dict.popitem() Remove and return last key-value pair {"a": 1, "b": 2}.popitem() → ('b', 2)
dict.clear() Clear dictionary {"a": 1, "b": 2}.clear() → {}
dict.update(other_dict) Update with another dictionary {"a": 1}.update({"b": 2}) → {"a": 1, "b": 2}
dict.copy() Return shallow copy of dictionary {"a": 1, "b": 2}.copy() → {"a": 1, "b": 2}
dict.fromkeys(keys, value) Create dictionary with keys and value dict.fromkeys(["a", "b"], 0) → {"a": 0, "b": 0}
key in dict Check if key exists "a" in {"a": 1, "b": 2} → True
dict.setdefault(key, default) Get value or set default if key not exists {"a": 1}.setdefault("b", 2) → 2
dict1 \| dict2 Merge two dictionaries {"a": 1} \| {"b": 2} → {"a": 1, "b": 2}

Set

Syntax Purpose Example
set([1, 2, 3]) Create set from list set([1, 2, 3]) → {1, 2, 3}
set.add(item) Add item to set {1, 2}.add(3) → {1, 2, 3}
set.remove(item) Remove item from set {1, 2, 3}.remove(2) → {1, 3}
set.discard(item) Remove item if exists {1, 2, 3}.discard(2) → {1, 3}
set.pop() Remove and return arbitrary item {1, 2, 3}.pop() → 1 (or 2 or 3)
set.clear() Remove all items from set {1, 2, 3}.clear() → set()
set.union(other_set) Union of two sets {1, 2}.union({3, 4}) → {1, 2, 3, 4}
set.intersection(other_set) Intersection of two sets {1, 2}.intersection({2, 3}) → {2}
set.difference(other_set) Difference of two sets {1, 2}.difference({2, 3}) → {1}
set.symmetric_difference(other_set) Symmetric difference of two sets {1, 2}.symmetric_difference({2, 3}) → {1, 3}
set.issubset(other_set) Check if set is subset {1}.issubset({1, 2}) → True
set.issuperset(other_set) Check if set is superset {1, 2}.issuperset({1}) → True
set.copy() Return shallow copy of set {1, 2}.copy() → {1, 2}
set.update(other_set) Update set with another set {1, 2}.update({3, 4}) → {1, 2, 3, 4}
set.intersection_update(other_set) Update set with intersection {1, 2}.intersection_update({2, 3}) → {2}
set.difference_update(other_set) Update set with difference {1, 2}.difference_update({2, 3}) → {1}
set.symmetric_difference_update(other_set) Update set with symmetric difference {1, 2}.symmetric_difference_update({2, 3}) → {1, 3}
len(set) Get number of items in set len({1, 2, 3}) → 3
item in set Check if item exists in set 1 in {1, 2, 3} → True
set1 \| set2 Union of two sets {1, 2} \| {3, 4} → {1, 2, 3, 4}
set1 & set2 Intersection of two sets {1, 2} & {2, 3} → {2}
set1 - set2 Difference of two sets {1, 2} - {2, 3} → {1}
set1 ^ set2 Symmetric difference of two sets {1, 2} ^ {2, 3} → {1, 3}

Tuple

Syntax Purpose Example
tuple([1, 2, 3]) Create tuple from list tuple([1, 2, 3]) → (1, 2, 3)
tuple.count(item) Count occurrences of item (1, 2, 3).count(2) → 1
tuple.index(item) Return index of first occurrence (1, 2, 3).index(2) → 1
len(tuple) Get length of tuple len((1, 2, 3)) → 3
item in tuple Check if item exists in tuple 1 in (1, 2, 3) → True
tuple1 + tuple2 Concatenate two tuples (1, 2) + (3, 4) → (1, 2, 3, 4)
tuple1 * n Repeat tuple n times (1, 2) * 2 → (1, 2, 1, 2)
tuple[0] Access first element of tuple (1, 2, 3)[0] → 1
tuple[-1] Access last element of tuple (1, 2, 3)[-1] → 3
tuple[1:3] Slice tuple from index 1 to 2 (1, 2, 3)[1:3] → (2, 3)
tuple[:2] Slice tuple from start to index 1 (1, 2, 3)[:2] → (1, 2)
tuple[1:] Slice tuple from index 1 to end (1, 2, 3)[1:] → (2, 3)
tuple[::2] Slice tuple with step 2 (1, 2, 3, 4)[::2] → (1, 3)
tuple[::-1] Reverse tuple (1, 2, 3)[::-1] → (3, 2, 1)
tuple.index(item, start, end) Return index of item in range (1, 2, 3).index(2, 0, 3) → 1

Utility Functions

Function Use
print() Display output
max() Largest value
min() Smallest value
sum() Sum of values
round() Round to decimals
len() Count elements
sorted() Sort values
help() Documentation
type() Get type
dir() List attributes
id() Get object ID