我想知道如何在ggplot上添加回归线方程和R^2。我的代码是:

library(ggplot2)

df <- data.frame(x = c(1:100))
df$y <- 2 + 3 * df$x + rnorm(100, sd = 40)
p <- ggplot(data = df, aes(x = x, y = y)) +
            geom_smooth(method = "lm", se=FALSE, color="black", formula = y ~ x) +
            geom_point()
p

任何帮助都将不胜感激。

假设我有一个包含以下9行的文本文件:

foo

bar

baz

qux

quux

我如何使用Sublime Text 2删除所有四个空白/空行，只留下五行?

我想将Mockito模拟对象注入到Spring (3+) bean中，以便使用JUnit进行单元测试。我的bean依赖项目前是通过在私有成员字段上使用@Autowired注释注入的。

我考虑过使用ReflectionTestUtils。setField，但是我希望注入的bean实例实际上是一个代理，因此没有声明目标类的私有成员字段。我不希望为依赖项创建公共setter，因为我将纯粹为了测试目的而修改我的接口。

我遵循了Spring社区提供的一些建议，但模拟没有被创建，自动连接失败:

<bean id="dao" class="org.mockito.Mockito" factory-method="mock">
    <constructor-arg value="com.package.Dao" />
</bean>

我目前遇到的错误如下:

...
Caused by: org...NoSuchBeanDefinitionException:
    No matching bean of type [com.package.Dao] found for dependency:
    expected at least 1 bean which qualifies as autowire candidate for this dependency.
    Dependency annotations: {
        @org...Autowired(required=true),
        @org...Qualifier(value=dao)
    }
at org...DefaultListableBeanFactory.raiseNoSuchBeanDefinitionException(D...y.java:901)
at org...DefaultListableBeanFactory.doResolveDependency(D...y.java:770)

如果我将constructor-arg值设置为无效的值，那么在启动应用程序上下文时就不会出现错误。

我有一个使用Spring Security的Spring MVC web应用程序。我想知道当前登录用户的用户名。我正在使用下面给出的代码片段。这是公认的方式吗?

我不喜欢在这个控制器中调用静态方法——恕我直言，这违背了Spring的全部目的。有没有一种方法来配置应用程序有当前的SecurityContext，或当前的认证，注入代替?

  @RequestMapping(method = RequestMethod.GET)
  public ModelAndView showResults(final HttpServletRequest request...) {
    final String currentUser = SecurityContextHolder.getContext().getAuthentication().getName();
    ...
  }

为什么在训练期间需要调用zero_grad() ?

|  zero_grad(self)
|      Sets gradients of all model parameters to zero.

我如何传递上下文到setTimeout?如果this.options.destroyOnHide在1000毫秒后，我想调用this.tip.destroy()。我该怎么做呢?

if (this.options.destroyOnHide) {
     setTimeout(function() { this.tip.destroy() }, 1000);
} 

当我尝试上面的时候，这指的是窗口。

我观察到rand()库函数在循环中只被调用一次时，它几乎总是产生正数。

for (i = 0; i < 100; i++) {
    printf("%d\n", rand());
}

但是当我添加两次rand()调用时，生成的数字现在有更多的负数。

for (i = 0; i < 100; i++) {
    printf("%d = %d\n", rand(), (rand() + rand()));
}

有人能解释一下为什么我在第二种情况下看到负数吗?

PS:我在循环之前将种子初始化为srand(time(NULL))。

这个问题几乎说明了一切。使用JPARepository我如何更新一个实体?

JPARepository只有一个save方法，它并没有告诉我它是创建还是更新。例如，我插入一个简单的对象到数据库User，它有三个字段:姓，名和年龄:

 @Entity
 public class User {

  private String firstname;
  private String lastname;
  //Setters and getters for age omitted, but they are the same as with firstname and lastname.
  private int age;

  @Column
  public String getFirstname() {
    return firstname;
  }
  public void setFirstname(String firstname) {
    this.firstname = firstname;
  }

  @Column
  public String getLastname() {
    return lastname;
  }
  public void setLastname(String lastname) {
    this.lastname = lastname;
  }

  private long userId;

  @Id
  @GeneratedValue(strategy=GenerationType.AUTO)
  public long getUserId(){
    return this.userId;
  }

  public void setUserId(long userId){
    this.userId = userId;
  }
}

然后我简单地调用save()，这在这一点上实际上是插入到数据库:

 User user1 = new User();
 user1.setFirstname("john"); user1.setLastname("dew");
 user1.setAge(16);

 userService.saveUser(user1);// This call is actually using the JPARepository: userRepository.save(user);

到目前为止一切顺利。现在我要更新这个用户，比如改变他的年龄。为此，我可以使用QueryDSL或NamedQuery之类的查询。但是，考虑到我只想使用spring-data-jpa和JPARepository，我如何告诉它我想做更新而不是插入呢?

具体来说，我如何告诉spring-data-jpa具有相同用户名和名字的用户实际上是EQUAL，并且现有实体应该被更新?重写等号并不能解决这个问题。

如何通过ssh连接到AWS实例?

我有:

Signed up at AWS; Created a public key and a certificate at AWS website and saved them to disk; Went to my console and created environment variables: $ export JAVA_HOME=/usr/lib/jvm/java-6-openjdk/ $ export EC2_CERT=/home/default/aws/cert-EBAINCRNWHDSCWWIHSOKON2YWGJZ5LSQ.pem $ export EC2_PRIVATE_KEY=/home/default/aws/pk-EBAINCRNWHDSCWWIHSOKON2YWGJZ5LSQ.pem Told AWS API to use this keypair and saved the keypair to file: $ ec2-add-keypair ec2-keypair > ec2-keypair.pem Started an AWS Ubuntu 9 instance using this keypair: $ ec2-run-instances ami-ed46a784 -k ec2-keypair Attempted to establish a ssh connection to the instance: $ ssh -v -i ec2-keypair.pem ubuntu@ec2-174-129-185-190.compute-1.amazonaws.com OpenSSH_5.1p1 Debian-5ubuntu1, OpenSSL 0.9.8g 19 Oct 2007 debug1: Reading configuration data /etc/ssh/ssh_config debug1: Applying options for * debug1: Connecting to ec2-174-129-185-190.compute-1.amazonaws.com [174.129.185.190] port 22. debug1: Connection established. debug1: identity file ec2-keypair.pem type -1 debug1: Remote protocol version 2.0, remote software version OpenSSH_5.1p1 Debian-5ubuntu1 debug1: match: OpenSSH_5.1p1 Debian-5ubuntu1 pat OpenSSH* debug1: Enabling compatibility mode for protocol 2.0 debug1: Local version string SSH-2.0-OpenSSH_5.1p1 Debian-5ubuntu1 debug1: SSH2_MSG_KEXINIT sent debug1: SSH2_MSG_KEXINIT received debug1: kex: server->client aes128-cbc hmac-md5 none debug1: kex: client->server aes128-cbc hmac-md5 none debug1: SSH2_MSG_KEX_DH_GEX_REQUEST(1024<1024<8192) sent debug1: expecting SSH2_MSG_KEX_DH_GEX_GROUP debug1: SSH2_MSG_KEX_DH_GEX_INIT sent debug1: expecting SSH2_MSG_KEX_DH_GEX_REPLY debug1: Host 'ec2-174-129-185-190.compute-1.amazonaws.com' is known and matches the RSA host key. debug1: Found key in /home/default/.ssh/known_hosts:11 debug1: ssh_rsa_verify: signature correct debug1: SSH2_MSG_NEWKEYS sent debug1: expecting SSH2_MSG_NEWKEYS debug1: SSH2_MSG_NEWKEYS received debug1: SSH2_MSG_SERVICE_REQUEST sent debug1: SSH2_MSG_SERVICE_ACCEPT received debug1: Authentications that can continue: publickey debug1: Next authentication method: publickey debug1: Trying private key: ec2-keypair.pem debug1: read PEM private key done: type RSA debug1: Authentications that can continue: publickey debug1: No more authentication methods to try. Permission denied (publickey). What could be the problem and how to make it work?

我想添加oracle jdbc驱动程序到我的项目作为依赖(运行时范围)- ojdbc14。 在MVNrepository站点中，要放在POM中的依赖项是:

<dependency>
    <groupId>com.oracle</groupId>
    <artifactId>ojdbc14</artifactId>
    <version>10.2.0.3.0</version>
</dependency>

当然，这是行不通的，因为它不在maven使用的中央存储库中。 两个问题:

我如何找到包含此工件的存储库(如果有的话)? 如何添加它以便Maven使用它?