大约有 5,475 项符合查询结果（耗时：0.0303秒） [XML]
JOIN queries vs multiple queries
...
100
For inner joins, a single query makes sense, since you only get matching rows.
For left joins,...
NumPy: function for simultaneous max() and min()
...90
And now we're in a place where we can test it:
import timeit
size = 100000
repeat = 10000
print timeit.timeit(
'np.min(a); np.max(a)',
setup='import numpy as np; a = np.arange(%d, dtype=np.float32)' % size,
number=repeat), " # numpy min/max"
print timeit.timeit(
'untitled.mi...
Is there a generator version of `string.split()` in Python?
... where memory isn't an issue anyway.
Tested using timeit on:
the_text = "100 " * 9999 + "100"
def test_function( method ):
def fn( ):
total = 0
for x in method( the_text ):
total += int( x )
return total
return fn
This raises another question as to...
Global and local variables in R
...
Here you have a small example:
test.env <- new.env()
assign('var', 100, envir=test.env)
# or simply
test.env$var <- 100
get('var') # var cannot be found since it is not defined in this environment
get('var', envir=test.env) # now it can be found
...
Converting between strings and ArrayBuffers
...4,114,97,121,32,99,111,110,118,101,114,116,
101,100,32,116,111,32,97,32,115,116,114,105,110,103]);
console.log(enc.decode(arr));
The MDN StringView library
An alternative to these is to use the StringView library (licensed as lgpl-3.0) which goal is:
to cre...
How do I undo the most recent local commits in Git?
...01: bad commit # Latest commit. This would be called 'HEAD'.
commit 100: good commit # Second to last commit. This is the one we want.
To restore everything back to the way it was prior to the last commit, we need to reset to the commit before HEAD:
git reset --soft HEAD^ # Use --soft ...
Scala list concatenation, ::: vs ++
...ntTimeMillis - t}
scala>def average(a: () => Long) = (for(i<-1 to 100) yield a()).sum/100
scala>average (() => time { (List[Int]() /: (1 to 1000)) { case (l, e) => l ++ List(e) } })
res1: Long = 46
scala>average (() => time { (List[Int]() /: (1 to 1000)) { case (l, e) => ...
Pandas: create two new columns in a dataframe with values calculated from a pre-existing column
...s also much faster on larger DataFrames
df = pd.DataFrame({'a': [1,2,3] * 100000, 'b': [2,3,4] * 100000})
DataFrame created with 300,000 rows
%timeit df["A1"], df["A2"] = calculate(df['a'])
2.65 ms ± 92.4 µs per loop (mean ± std. dev. of 7 runs, 100 loops each)
%timeit df["A1"], df["A2"] = z...
Can I serve multiple clients using just Flask app.run() as standalone?
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What if I am looking at a max of 100 users? Can I just assign processes=100 and be happy with it? In my case, I only need static files, no HTTP Post methods. My requirement is, I want to run all Flask threads as part of my parent app, so that they all can sh...
Bootstrap combining rows (rowspan)
...
100
Divs stack vertically by default, so there is no need for special handling of "rows" within a ...