Queues
Priority Queue |
from queue import PriorityQueue |
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customers = PriorityQueue() |
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customers.put((2, "Harry")) |
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while customers: |
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print(customers.get()) |
Heaps
import heapq |
heapq.heapify(li) |
transform array "li" into min-heap |
heapq._heapify_max(li) |
transform array "li" into max-heap |
heapq.heappush(li,4) |
push element in the heap |
heapq.heappop(li) |
pop the smallest element |
heapq.nlargest(3, li1) |
get the 3 largest numbers |
heapq.nsmallest(3, li1) |
get the 3 smallest numbers |
heapq.nsmallest(3, tuple_list, key=lambda x: x[1]) |
if we want 3 smallest tuple_list second dimension |
Deque
deque sized |
window = deque(maxlen=3) |
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String
Split |
string.split(" ", 1) //split first occ |
Replace |
str.replace('e', '') |
Replace first occurrence |
str.replace('e', '',1) |
Remove symbols from phrase |
paragraph = ''.join([c.lower() if c.isalnum() else ' ' for c in paragraph]) |
check array if matches |
banned_words = set(banned)
for word in toCount:
if word not in banned_words:
... |
Arrays
array of set capacity |
LRUcache = [] * capacity |
sort to new |
new_list = sorted(old_list, key=..., reverse=...) |
sort in place |
list.sort(key=..., reverse=...) |
sort by len |
list.sort(key=len) |
sort column |
def takeSecond(elem):
return elem[1]
list.sort(key=takeSecond) |
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Dict
create dict |
dict = {} |
return keys arr |
dict.keys() |
return values arr |
dict.values() |
order a dict by value |
from operator import itemgetter
sorted_keys = sorted(toReduce.items(), key=itemgetter(1)) |
orderdict |
from collections import OrderedDict
d = OrderedDict()
d.move_to_end('key') |
orderdict by value |
from collections import OrderedDict
from operator import itemgetter
OrderedDict(sorted(d.items(), key = itemgetter(1), reverse = True)) |
put in first position |
d.move_to_end('key',last=False) |
comprehension list val*2 |
dict_variable = {key:value*2 for (key,value) in dictonary.items()} |
dict with array as key |
dictionary[tuple(arr)] = val |
Classes
initialise |
__init__(self, var1, var2) |
create iterable |
__iter__(self) |
Files
Read file |
wfile = open(wordFile, ' r') |
split line |
for line in wfile:
word = line[:-1] |
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