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Create list of single item repeated N times
...ts . To create unique empty sub-lists, use for-comprehension: [[] for i in range(0,n)]
– Josiah Yoder
Aug 15 '17 at 17:01
...
What is the recommended way to delete a large number of items from DynamoDB?
... want to do is call LogTable.DeleteItem(user_id) -
Without supplying the range, and have it delete everything for me.
An understandable request indeed; I can imagine advanced operations like these might get added over time by the AWS team (they have a history of starting with a limited feature s...
MySql: Tinyint (2) vs tinyint(1) - what is the difference?
...isplay width.
It's important to note that it does not affect the accepted range of values for that particular type, i.e. TINYINT(1) still accepts [-128 .. 127].
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Automatically create an Enum based on values in a database lookup table?
...t to the name of an enumeration. The enumeration restricts the valid value range for a different property of the same object. In my case I'm loading metadata, including the valid value range from a database; and no, the vendor code does not support passing a collection of any type to the property. T...
Are tuples more efficient than lists in Python?
... advantage:
>>> import sys
>>> sys.getsizeof(tuple(iter(range(10))))
128
>>> sys.getsizeof(list(iter(range(10))))
200
Here is the comment from Objects/listobject.c that explains what lists are doing:
/* This over-allocates proportional to the list size, making room
* ...
How to think in data stores instead of databases?
...ey, and fetch operations are limited to fetching single keys or contiguous ranges of keys. More sophisticated queries are made possible with indexes, which are basically just tables of their own, allowing you to implement more complex queries as scans on contiguous ranges.
Once you've absorbed that,...
What makes Scala's operator overloading “good”, but C++'s “bad”?
...rators may be used infix that puts pressure on people to try to map a wide range of unrelated concepts onto a relatively few symbols like "+" and ">>"
Scala allows a huge range of valid non-word symbols as method names. For instance, I've got an embedded Prolog-ish DSL where you can write
...
Naming returned columns in Pandas aggregate function? [duplicate]
...ata frame
df = pd.DataFrame({'A': [1, 1, 1, 2, 2],
'B': range(5),
'C': range(5)})
# ==== SINGLE COLUMN (SERIES) ====
# Syntax soon to be deprecated
df.groupby('A').B.agg({'foo': 'count'})
# Recommended replacement syntax
df.groupby('A').B.agg(['count']).rename(...
How can I find the first occurrence of a sub-string in a python string?
...on .
This can be implemented as
def find_pos(string,word):
for i in range(len(string) - len(word)+1):
if string[i:i+len(word)] == word:
return i
return 'Not Found'
string = "the dude is a cool dude"
word = 'dude1'
print(find_pos(string,word))
# output 4
...
Enums and Constants. Which to use when?
...
Use enums when you want to define a range of values that something can be. Colour is an obvious example like:
public enum Colour
{
White,
Red,
Blue
}
Or maybe a set of possible things like:
(Example I stole from here as I'm lazy)
[FlagsAttribute...