大约有 21,000 项符合查询结果（耗时：0.0309秒） [XML]
Adding new column to existing DataFrame in Python pandas
...)
As per this example (which also includes the source code of the assign function), you can also include more than one column:
df = pd.DataFrame({'a': [1, 2], 'b': [3, 4]})
>>> df.assign(mean_a=df.a.mean(), mean_b=df.b.mean())
a b mean_a mean_b
0 1 3 1.5 3.5
1 2 4 1...
Null vs. False vs. 0 in PHP
...ill get inequality.
So why are they useful ?
Well, look at the strrpos() function. It returns False if it did not found anything, but 0 if it has found something at the beginning of the string !
<?php
// pitfall :
if (strrpos("Hello World", "Hello")) {
// never exectuted
}
// smart move ...
Insert, on duplicate update in PostgreSQL?
...RT, as appropriate:
CREATE TABLE db (a INT PRIMARY KEY, b TEXT);
CREATE FUNCTION merge_db(key INT, data TEXT) RETURNS VOID AS
$$
BEGIN
LOOP
-- first try to update the key
-- note that "a" must be unique
UPDATE db SET b = data WHERE a = key;
IF found THEN
...
What is the difference between cout, cerr, clog of iostream header in c++? When to use which one?
...::clog.rdbuf(clogbuf);
}
int main()
{
test();
std::cout << "123";
}
share
|
improve this answer
|
follow
|
...
Why not infer template parameter from constructor?
... infer template parameters from class constructors, much as it can do from function parameters? For example, why couldn't the following code be valid:
...
Does have to be in the of an HTML document?
...nswered Jun 24 '12 at 22:40
user123444555621user123444555621
123k2323 gold badges101101 silver badges120120 bronze badges
...
Check if a string is html or not
... purposes your app may want to detect these too.
– TK123
Sep 21 '16 at 19:39
HTML is designed with the forgiveness of ...
Tablet or Phone - Android
...
123
As it has been mentioned before, you do not want to check whether the device is a tablet or a ...
Is there a better way to express nested namespaces in C++ within the header
...races that were missing comments about which brace closes which scope? Not fun.).
MY_COMPANY_BEGIN
MY_LIBRARY_BEGIN
class X { };
class Y { };
MY_LIBRARY_END
MY_COMPANY_END
If you want to put all namespace declarations on a single line you can do that as well with a bit of (pretty ugly) preproc...
adb not finding my device / phone (MacOS X)
...w on port 5037 *
* daemon started successfully *
List of devices attached
123ABC456DEF001 device
share
|
improve this answer
|
follow
|
...