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Why does Java's hashCode() in String use 31 as a multiplier?
... i == (i << 5) - i. Modern VMs do this sort of optimization automatically.
(from Chapter 3, Item 9: Always override hashcode when you override equals, page 48)
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What is the most efficient way of finding all the factors of a number in Python?
Can someone explain to me an efficient way of finding all the factors of a number in Python (2.7)?
22 Answers
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Delete rows from a pandas DataFrame based on a conditional expression involving len(string) giving K
...df = df.drop(df[<some boolean condition>].index)
Example
To remove all rows where column 'score' is < 50:
df = df.drop(df[df.score < 50].index)
In place version (as pointed out in comments)
df.drop(df[df.score < 50].index, inplace=True)
Multiple conditions
(see Boolean Indexing...
SQL SELECT WHERE field contains words
...%'
OR column1 LIKE '%word2%'
OR column1 LIKE '%word3%'
If you need all words to be present, use this:
SELECT * FROM mytable
WHERE column1 LIKE '%word1%'
AND column1 LIKE '%word2%'
AND column1 LIKE '%word3%'
If you want something faster, you need to look into full text search, and this...
Python dictionary from an object's fields
...a dictionary from an arbitrary object, it's sufficient to use __dict__. Usually, you'll declare your methods at class level and your attributes at instance level, so __dict__ should be fine. For example:
>>> class A(object):
... def __init__(self):
... self.b = 1
... self.c = 2
....
Any reason to write the “private” keyword in C#?
... the defaults, as per your question (I've never liked this argument, personally, but I figured it's worth mentioning)
It gives an impression that you've deliberately decided to make it private, rather than just gone with the defaults.
As for your last part:
Moreover is there a case where writi...
What is the difference between iterator and iterable and how to use them?
I am new in Java and I'm really confused with iterator and iterable. Can anyone explain to me and give some examples?
13 An...
Bootstrap 3 panel header with buttons wrong position
...hat Panel Header gets pulled to the top of the div and the btn-group vertically aligns
– Nuno Furtado
Aug 7 '14 at 13:14
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Best Practices: working with long, multiline strings in PHP?
...idered to be a string as-is. Which means you don't need to put backslash n all over your multi-line strings. @Fabian: What is the difference between a HEREDOC and NOWDOC, or are they the same thing?
– Kenny Drobnack
Dec 4 '09 at 19:11
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Detect & Record Audio in Python
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Great example! Really useful when I tried to wrap my head around how to record voice using Python. One quick question I had is whether there is a way to define the time period of the recording. Now it records a word? Can I play with it and ha...