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Dependency Injection vs Factory Pattern
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+1 @willcode thanks! So you have to change config/xml files instead. I see. The wiki link en.wikipedia.org/wiki/… defines the factory pattern as Manually-Injected Dependency
– gideon
Dec 15 '10 at 3:16
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Using global variables in a function
...magine the reason for it is that, since global variables are so dangerous, Python wants to make sure that you really know that's what you're playing with by explicitly requiring the global keyword.
See other answers if you want to share a global variable across modules.
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What is memoization and how can I use it in Python?
I just started Python and I've got no idea what memoization is and how to use it. Also, may I have a simplified example?
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Using pickle.dump - TypeError: must be str, not bytes
I'm using python3.3 and I'm having a cryptic error when trying to pickle a simple dictionary.
2 Answers
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Logical operators for boolean indexing in Pandas
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When you say
(a['x']==1) and (a['y']==10)
You are implicitly asking Python to convert (a['x']==1) and (a['y']==10) to boolean values.
NumPy arrays (of length greater than 1) and Pandas objects such as Series do not have a boolean value -- in other words, they raise
ValueError: The truth v...
Python Regex instantly replace groups
...re.sub:
result = re.sub(r"(\d.*?)\s(\d.*?)", r"\1 \2", string1)
This is Python's regex substitution (replace) function. The replacement string can be filled with so-called backreferences (backslash, group number) which are replaced with what was matched by the groups. Groups are counted the same ...
Splitting on last delimiter in Python string?
What's the recommended Python idiom for splitting a string on the last occurrence of the delimiter in the string? example:
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Printing Lists as Tabular Data
I am quite new to Python and I am now struggling with formatting my data nicely for printed output.
13 Answers
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How to sort Counter by value? - python
... than doing list comprehensions of reversed list comprehension, is there a pythonic way to sort Counter by value? If so, it is faster than this:
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Solving “Who owns the Zebra” programmatically?
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Here's a solution in Python based on constraint-programming:
from constraint import AllDifferentConstraint, InSetConstraint, Problem
# variables
colors = "blue red green white yellow".split()
nationalities = "Norwegian German Dane Swed...