大约有 40,000 项符合查询结果（耗时：0.0364秒） [XML]
How to use base class's constructors and assignment operator in C++?
...
You can explicitly call constructors and assignment operators:
class Base {
//...
public:
Base(const Base&) { /*...*/ }
Base& operator=(const Base&) { /*...*/ }
};
class Derived : public Base
{
int additional_;
public:
...
MySQL ERROR 1045 (28000): Access denied for user 'bill'@'localhost' (using password: YES)
...ands.
The recommended solution is to drop this anonymous user (this is usually a good thing to do anyways).
Below edits are mostly irrelevant to the main question. These are only meant to answer some questions raised in other comments within this thread.
Edit 1
Authenticating as 'bill'@'%' thr...
Where can I learn how to write C code to speed up slow R functions? [closed]
...ds C++ and Rcpp to be much more like writing R than writing C++. YMMV and all that.
share
|
improve this answer
|
follow
|
...
Why is there no xrange function in Python3?
...Some performance measurements, using timeit instead of trying to do it manually with time.
First, Apple 2.7.2 64-bit:
In [37]: %timeit collections.deque((x for x in xrange(10000000) if x%4 == 0), maxlen=0)
1 loops, best of 3: 1.05 s per loop
Now, python.org 3.3.0 64-bit:
In [83]: %timeit collec...
How do I write a short literal in C++?
...rt enough to compile this as if it's a short literal (i.e. it wouldn't actually allocate an int and then cast it every time).
The following illustrates how much you should worry about this:
a = 2L;
b = 2.0;
c = (short)2;
d = '\2';
Compile -> disassemble ->
movl $2, _a
movl $2, _b
m...
Progress indicator during pandas operations
...se you're interested in how this works (and how to modify it for your own callbacks), see the examples on github, the full documentation on pypi, or import the module and run help(tqdm). Other supported functions include map, applymap, aggregate, and transform.
EDIT
To directly answer the original ...
How to plot two columns of a pandas data frame using points?
...
You can specify the style of the plotted line when calling df.plot:
df.plot(x='col_name_1', y='col_name_2', style='o')
The style argument can also be a dict or list, e.g.:
import numpy as np
import pandas as pd
d = {'one' : np.random.rand(10),
'two' : np.random.rand(...
Python Linked List
...le to reference separate parts of them. Make them immutable and they are really easy to work with!
28 Answers
...
SQLAlchemy: cascade delete
...use that is where you defined your relationship (it doesn't care that you called it "Child" of course).
If you define the relationship on the Parent class instead, it will work:
children = relationship("Child", cascade="all,delete", backref="parent")
(note "Child" as a string: this is allowed wh...
What does enumerate() mean?
...ieving that; one using itertools.count() to do the counting, the other manually counting in a generator function:
from itertools import count
def enumerate(it, start=0):
# return an iterator that adds a counter to each element of it
return zip(count(start), it)
and
def enumerate(it, sta...