小编use*_*159的帖子

我已经阅读了很多这个例外,但我无法解决我的问题.

Mysql服务器正在运行.

我可以从NetBeans连接到它,但我无法从java代码连接到它.

Exception in thread "main" com.mysql.jdbc.exceptions.jdbc4.CommunicationsException: Communications link failure

The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.SQLError.createCommunicationsException(SQLError.java:1116)
    at com.mysql.jdbc.MysqlIO.<init>(MysqlIO.java:344)
    at com.mysql.jdbc.ConnectionImpl.coreConnect(ConnectionImpl.java:2332)
    at com.mysql.jdbc.ConnectionImpl.connectOneTryOnly(ConnectionImpl.java:2369)
    at com.mysql.jdbc.ConnectionImpl.createNewIO(ConnectionImpl.java:2153)
    at com.mysql.jdbc.ConnectionImpl.<init>(ConnectionImpl.java:792)
    at com.mysql.jdbc.JDBC4Connection.<init>(JDBC4Connection.java:47)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:525)
    at com.mysql.jdbc.Util.handleNewInstance(Util.java:411)
    at com.mysql.jdbc.ConnectionImpl.getInstance(ConnectionImpl.java:381)
    at com.mysql.jdbc.NonRegisteringDriver.connect(NonRegisteringDriver.java:305)
    at java.sql.DriverManager.getConnection(DriverManager.java:579)
    at java.sql.DriverManager.getConnection(DriverManager.java:243)
    at javaapplication3.JavaApplication3.main(JavaApplication3.java:32)
Caused …

//对不起我的英语不好.

请告诉我,我做错了什么？我已经阅读了很多关于此的内容.并写一些代码,但我有一个可怕的结果.

据我所知,Opencv CV_8UC3与QImage :: Format_RGB888相同,但BRG和RGB除外.

以这种格式阅读cv :: Mat我能做到:

cv::Mat mat1 = cv::imread("bugero.jpg",3); 

所以,要将cv :: Mat转换为QImage,我可以这样做:

QImage Mat2QImage(cv::Mat const& src)
{
     cv::Mat temp(src.cols,src.rows,src.type());
     cvtColor(src, temp,CV_BGR2RGB);
     QImage dest= QImage((uchar*) temp.data, temp.cols, temp.rows, temp.step, QImage::Format_RGB888);
     return dest;
}

我做了临时垫因为我想在QImage中拥有数据副本.

然后.要将其转换回来,我必须这样做:

cv::Mat QImage2Mat(QImage const& src)
{
     QImage temp = src.copy();
     cv::Mat res(temp.height(),temp.width(),CV_8UC3,(uchar*)temp.bits(),temp.bytesPerLine());
     cvtColor(res, res,CV_BGR2RGB); 
     return res;
}

我插入了cvtColor(res,res,CV_BGR2RGB) ; 使用BGR颜色制作cv Mat.我不知道这个函数里面有什么cvtColor(res,res,CV_BGR2RGB) ;但是我决定如果cvtColor(res,res,CV_BGR2RGB); 改变地方R和B,这将使这些颜色的地方变回,因为我没有找到CV_BGR2RGB.

所以,我写了一个简短的示例程序

#include <QApplication>
#include <QtGui>
#include <cv.h>
#include "opencv2/highgui/highgui.hpp"

QImage Mat2QImage(cv::Mat …

我在matplotlib尝试networkx和可视化我很困惑因为我不清楚他们如何互相交流？有简单的例子

import matplotlib.pyplot
import networkx as nx
G=nx.path_graph(8)
nx.draw(G)
matplotlib.pyplot.show()

我在哪里告诉pyplot,我想绘制图G？我猜nx.draw使用像matplotlib.pyplot这样的东西.{plot,etc ...}所以,如果我想绘制2个图:

import matplotlib.pyplot
import networkx as nx

G=nx.path_graph(8)
E=nx.path_graph(30)
nx.draw(G)

matplotlib.pyplot.figure()
nx.draw(E)
matplotlib.pyplot.show()

然后......小实验

import networkx as nx
G=nx.path_graph(8)
E=nx.path_graph(30)
nx.draw(G)
import matplotlib.pyplot
matplotlib.pyplot.figure()
nx.draw(E)
import matplotlib.pyplot as plt
plt.show()

请不要因为这个愚蠢的代码而杀了我,我只是想了解 - networkx如何绘制matplotlib的东西,而它甚至还没有导入!

PS:抱歉我的英文.