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Group by multiple columns in dplyr, using string vector input
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Does the call to one_of() do anything here? I think it is redundant in this context, as the expression is wrapped in a call to vars().
– knowah
Aug 15 '19 at 14:13
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Execute method on startup in Spring
...n and it executes just after the startup, but then it will execute periodically.
13 Answers
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Determine if Python is running inside virtualenv
...r sys.base_prefix did not ever exist. So a fully robust check that handles all of these cases could look like this:
import sys
def get_base_prefix_compat():
"""Get base/real prefix, or sys.prefix if there is none."""
return getattr(sys, "base_prefix", None) or getattr(sys, "real_prefix", No...
Python decorators in classes
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Would something like this do what you need?
class Test(object):
def _decorator(foo):
def magic( self ) :
print "start magic"
foo( self )
print "end magic"
return magic
@_decorator
def bar( self ) :
print "normal call"
test ...
导盲项目：什么场景非得用相机预览？按杖上按钮或定时拍照，识别后语音提醒...
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Why 0 is true but false is 1 in the shell?
The above will output 1 , which is contradictory with all other programming languages I know.
10 Answers
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How to select only the first rows for each unique value of a column
... which is a counter that increments every time it sees the same CName, and indexes those occurrences by AddressLine. By imposing where row = 1, one can select the CName whose AddressLine comes first alphabetically. If the order by was desc, then it would pick the CName whose AddressLine comes last a...
Best way to parse command-line parameters? [closed]
What's the best way to parse command-line parameters in Scala?
I personally prefer something lightweight that does not require external jar.
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Collection that allows only unique items in .NET?
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If all you need is to ensure uniqueness of elements, then HashSet is what you need.
What do you mean when you say "just a set implementation"? A set is (by definition) a collection of unique elements that doesn't save element ...
How to refer to relative paths of resources when working with a code repository
...Try to use a filename relative to the current files path. Example for './my_file':
fn = os.path.join(os.path.dirname(__file__), 'my_file')
In Python 3.4+ you can also use pathlib:
fn = pathlib.Path(__file__).parent / 'my_file'
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