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Pandas every nth row
...simpler solution to the accepted answer that involves directly invoking df.__getitem__.
df = pd.DataFrame('x', index=range(5), columns=list('abc'))
df
a b c
0 x x x
1 x x x
2 x x x
3 x x x
4 x x x
For example, to get every 2 rows, you can do
df[::2]
a b c
0 x x x
...
Do I have to guard against SQL injection if I used a dropdown?
...pect.
$possibleOptions = array('All', 'Large', 'Medium', 'Small');
if(in_array($_POST['size'], $possibleOptions)) {
// Expected
} else {
// Not Expected
}
Then use mysqli_* if you are using a version of php >= 5.3.0 which you should be, to save your result. If used correctly this wil...
Custom thread pool in Java 8 parallel stream
...gt;
// Parallel task here, for example
IntStream.range(1, 1_000_000).parallel()
.filter(PrimesPrint::isPrime)
.boxed().collect(Collectors.toList())
).get();
System.out.println(primes);
} catch (InterruptedException | ExecutionException e) {
...
What does Ruby have that Python doesn't, and vice versa?
...ound as an object, and overwrite it:
def func(): print "hello"
def another_func(f): f()
another_func(func)
def func2(): print "goodbye"
func = func2
This is a fundamental feature of modern scripting languages. JavaScript and Lua do this, too. Ruby doesn't treat functions this way; naming a fun...
What breaking changes are introduced in C++11?
...bc"
const char *s = u8"def"; // Previously "abcdef", now "def"
#define _x "there"
"hello"_x // now a user-defined-string-literal. Previously, expanded _x .
New keywords: alignas, alignof, char16_t, char32_t, constexpr, decltype, noexcept, nullptr, static_assert, and thread_local
Ce...
Efficiently convert rows to columns in sql server
... for ColumnName in (' + @cols + N')
) p '
exec sp_executesql @query;
See Demo.
Using an aggregate function
If you do not want to use the PIVOT function, then you can use an aggregate function with a CASE expression:
select
max(case when columnname = 'FirstName' then ...
How do I move files in node.js?
...e rename function to do that.
http://nodejs.org/docs/latest/api/fs.html#fs_fs_rename_oldpath_newpath_callback
fs.rename(oldPath, newPath, callback)
Added in: v0.0.2
oldPath <String> | <Buffer>
newPath <String> | <Buffer>
callback <Function>
Asynchronous...
Why use sprintf function in PHP?
... get the rightly aligned 8 digit and commas separated integer. Using number_format is less convenient in a printf style.
– e2-e4
Nov 16 '10 at 6:41
...
Force browser to clear cache
... changes, one way is to to "cache busting" is by appending something like "_versionNo" to the file name for each release. For example:
script_1.0.css // This is the URL for release 1.0
script_1.1.css // This is the URL for release 1.1
script_1.2.css // etc.
Or alternatively do it after the fil...
What does numpy.random.seed(0) do?
...
If you set the np.random.seed(a_fixed_number) every time you call the numpy's other random function, the result will be the same:
>>> import numpy as np
>>> np.random.seed(0)
>>> perm = np.random.permutation(10)
>>> p...