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Python: Check if one dictionary is a subset of another larger dictionary
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112
Convert to item pairs and check for containment.
all(item in superset.items() for item in subse...
Transposing a NumPy array
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248
It's working exactly as it's supposed to. The transpose of a 1D array is still a 1D array! (I...
What is the difference between shallow copy, deepcopy and normal assignment operation?
... the
original.
Here's a little demonstration:
import copy
a = [1, 2, 3]
b = [4, 5, 6]
c = [a, b]
Using normal assignment operatings to copy:
d = c
print id(c) == id(d) # True - d is the same object as c
print id(c[0]) == id(d[0]) # True - d[0] is the same object as c[0]
Us...
The tilde operator in Python
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204
It is a unary operator (taking a single argument) that is borrowed from C, where all data type...
Is it possible to have multiple statements in a python lambda expression?
...found in the heapq module.
>>> import heapq
>>> l = [5,2,6,8,3,5]
>>> heapq.nsmallest(l, 2)
[2, 3]
So just use:
map(lambda x: heapq.nsmallest(x,2)[1], list_of_lists)
It's also usually considered clearer to use a list comprehension, which avoids the lambda altogethe...
pandas DataFrame: replace nan values with average of columns
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283
You can simply use DataFrame.fillna to fill the nan's directly:
In [27]: df
Out[27]:
...
How to split a sequence into two pieces by predicate?
...
By using partition method:
scala> List(1,2,3,4).partition(x => x % 2 == 0)
res0: (List[Int], List[Int]) = (List(2, 4),List(1, 3))
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How to implement a queue using two stacks?
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How to read data From *.CSV file using javascript?
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122
NOTE: I concocted this solution before I was reminded about all the "special cases" that can oc...
Oracle “(+)” Operator
...s) didn't standardize OUTER joins.
The query would be re-written in ANSI-92 syntax as:
SELECT ...
FROM a
LEFT JOIN b ON b.id = a.id
This link is pretty good at explaining the difference between JOINs.
It should also be noted that even though the (+) works, Oracle recommends not using ...