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Logical operators for boolean indexing in Pandas
...Error: The truth value of an array is ambiguous. Use a.empty, a.any() or a.all().
when used as a boolean value. That's because its unclear when it should be True or False. Some users might assume they are True if they have non-zero length, like a Python list. Others might desire for it to be True ...
Get exception description and stack trace which caused an exception, all as a string
...
See the traceback module, specifically the format_exc() function. Here.
import traceback
try:
raise ValueError
except ValueError:
tb = traceback.format_exc()
else:
tb = "No error"
finally:
print tb
...
Chaining multiple filter() in Django, is this a bug?
I always assumed that chaining multiple filter() calls in Django was always the same as collecting them in a single call.
4...
Inverse dictionary lookup in Python
...o guarantee that it returns a single value and it does not need to be lexically first only that it be the first match and that it's behavior is stable (multiple calls on same dict over time should yield same matching element). Unless dictionaries rearrange their unmodified hashes over time as other...
How do I list all files of a directory?
How can I list all files of a directory in Python and add them to a list ?
21 Answers
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Elasticsearch query to return all records
I have a small database in Elasticsearch and for testing purposes would like to pull all records back. I am attempting to use a URL of the form...
...
What do I use for a max-heap implementation in Python?
... amazed that there IS such a built-in solution in heapq. But then it is totally unreasonable that it is NOT even slightly mentioned at all in the official document! WTF!
– RayLuo
Apr 21 '15 at 6:48
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What optimizations can GHC be expected to perform reliably?
...has a lot of optimizations that it can perform, but I don't know what they all are, nor how likely they are to be performed and under what circumstances.
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Understanding __get__ and __set__ and Python descriptors
...th the Temperature class). For example:
temp=Temperature()
temp.celsius #calls celsius.__get__
Accessing the property you assigned the descriptor to (celsius in the above example) calls the appropriate descriptor method.
instance in __get__ is the instance of the class (so above, __get__ would r...
method of iterating over sqlalchemy model's defined columns?
...l exclude SA magic attributes, but will not exclude the relations. So basically it might load the dependencies, parents, children etc, which is definitely not desirable.
But it is actually much easier because if you inherit from Base, you have a __table__ attribute, so that you can do:
for c in Jo...