Python Data Structures and Their Methods

append(x)

Add item to end of list

pop([i])

Remove and return item (default is last)

insert(i, x)

Insert item at index

remove(x)

Remove first occurrence of value

reverse()

Reverse list in place

sort()

Sort list in place

extend(iterable)

Add items from another iterable

count(x)

Count number of times value appears

index(x)

Return first index of value

len(lst)

Get number of elements

list[start:end:step]

Slice list

add(x)

Add element

discard(x)

Remove if exists

union(set2)

Combine sets

intersection(set2)

Common elements

difference(set2)

Elements in one but not the other

in

Check membership

len(set)

Get size

get(key, default)

Get value or default

keys()

All keys

values()

All values

items()

All key-value pairs

pop(key)

Remove key and return value

update(other_dict)

Add/replace items from another dict

len(dict)

Number of key-value pairs

split(sep)

Split into list

join(list)

Join list into string

strip()

Remove surrounding whitespace

startswith(s)

Check start

endswith(s)

Check end

replace(old, new)

Replace substring

find(s)

Find index of substring

lower()

To lowercase

upper()

To uppercase

len(s)

Length of string

s[start:end]

Slice string

range(n)

Sequence from 0 to n-1

enumerate(iterable)

Index + value

zip(a, b)

Pair elements

map(func, iterable)

Apply function

filter(func, iterable)

Filter by function

any(iterable)

True if any True

all(iterable)

True if all True

sum(iterable)

Total of items

max(iterable)

Largest value

min(iterable)

Smallest value

sorted(iterable)

Return sorted version

heapq.heappush(heap, x)

Add to min-heap

heapq.heappop(heap)

Remove min from heap

deque.append(x)

Add to right side

deque.popleft()

Remove from left side

collections.Counter()

Count frequencies

collections.defaultdict(type)

Auto-creating dict