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How to access pandas groupby dataframe by key
...ionally - turn it all back into a single dataframe object
sampled_df = pd.concat(df_list, axis=0, join='outer')
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How to find current transaction level?
... SET
ansi_padding SET
ansi_nulls SET
concat_null_yields_null SET
isolation level read committed
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What is the best way to concatenate two vectors?
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Depends on whether you really need to physically concatenate the two vectors or you want to give the appearance of concatenation of the sake of iteration. The boost::join function
http://www.boost.org/doc/libs/1_43_0/libs/range/doc/html/range/reference/utilities/join.html
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Stop Excel from automatically converting certain text values to dates
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In my MySQL query (for CSV output through PHP), I used CONCAT('\t', column_name). Also did the trick. Thanks!
– Just Plain High
Jun 24 '16 at 14:39
1
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Lua简明教程 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...应表达式 a ^ b
__unm(a) 对应表达式 -a
__concat(a, b) 对应表达式 a .. b
__len(a) 对应表达式 #a
__eq(a, b) 对应表达式 a == b
__lt(a, b) 对应表达式 a < b
__le(a, b...
Convert pandas dataframe to NumPy array
...early the same (actually, using rec.fromrecords is a bit faster).
df2 = pd.concat([df] * 10000)
%timeit df2.to_records()
%%timeit
v = df2.reset_index()
np.rec.fromrecords(v, names=v.columns.tolist())
11.1 ms ± 557 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
9.67 ms ± 126 µs per l...
String.Join method that ignores empty strings?
...nce you can do it in SQL directly:
PostgreSQL & MySQL:
SELECT
concat_ws(' / '
, NULLIF(searchTerm1, '')
, NULLIF(searchTerm2, '')
, NULLIF(searchTerm3, '')
, NULLIF(searchTerm4, '')
) AS RPT_SearchTerms;
And even with the glorious MS-SQL-Server it'...
Creating C macro with ## and __LINE__ (token concatenation with positioning macro)
...or is expected to for decades. The prime example is compiling X11, macro "Concat3" is broken, it's result is now MISNAMED C Identifier, which of course fails to build. and i'm beginning to thing build fails are their profession.
I think the answer here is "new C that breaks standards is bad C", t...
How can I generate random alphanumeric strings?
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@Adam: Yes, you could concat the result of multiple calls to GetRandomFileName but then (a) you'd lose your performance advantage, and (b) your code would become more complicated.
– LukeH
Aug 28 '09 at 9:08
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No provider for “framework:jasmine”! (Resolving: framework:jasmine)
...ffee": "~0.7.0",
"grunt-contrib-compass": "~0.6.0",
"grunt-contrib-concat": "~0.3.0",
"grunt-contrib-connect": "~0.5.0",
"grunt-contrib-copy": "~0.4.1",
"grunt-contrib-cssmin": "~0.7.0",
"grunt-contrib-htmlmin": "~0.1.3",
"grunt-contrib-imagemin": "~0.3.0",
"grunt-con...