小编Kla*_*sos的帖子

如何知道特定年份的特定月份有多少天？

String date = "2010-01-19";
String[] ymd = date.split("-");
int year = Integer.parseInt(ymd[0]);
int month = Integer.parseInt(ymd[1]);
int day = Integer.parseInt(ymd[2]);
Calendar calendar = Calendar.getInstance();
calendar.set(Calendar.YEAR,year);
calendar.set(Calendar.MONTH,month);
int daysQty = calendar.getDaysNumber(); // Something like this

我需要适应RandomForestRegressor的sklearn.ensemble.

forest = ensemble.RandomForestRegressor(**RF_tuned_parameters)
model = forest.fit(train_fold, train_y)
yhat = model.predict(test_fold)

这段代码一直有效,直到我对data(train_y)进行了一些预处理.错误消息说:

DataConversionWarning:当期望1d数组时传递列向量y.请将y的形状更改为(n_samples,),例如使用ravel().

model = forest.fit(train_fold,train_y)

以前train_y是一个系列,现在它是numpy数组(它是一个列向量).如果我应用train_y.ravel(),那么它变成行向量并且没有出现错误消息,通过预测步骤需要很长时间(实际上它永远不会完成......).

在RandomForestRegressor我发现的文档中train_y应该定义为y : array-like, shape = [n_samples] or [n_samples, n_outputs] 任何想法如何解决这个问题？

我想为_x每个列名添加后缀,如下所示:

featuresA = myPandasDataFrame.columns.values + '_x'

我该怎么做呢？另外,如果我想添加x_后缀,解决方案将如何变化？

启动应用程序时,不会选择任何行.但我想表明第一行已被选中.

这该怎么做？我需要设置一行的颜色JTable吗？

更新:我尝试了table.setRowSelectionInterval(0,0).我知道它应该工作,但有一条错误消息:

Exception in thread "AWT-EventQueue-0" java.lang.IllegalArgumentException: Row index out of range
    at javax.swing.JTable.boundRow(Unknown Source)
    at javax.swing.JTable.setRowSelectionInterval(Unknown Source)
    at cpn_gui.OptPanel.createForm(OptPanel.java:124)
    at cpn_gui.OptPanel.<init>(OptPanel.java:50)
    at cpn_gui.Login$1.actionPerformed(Login.java:62)
    at javax.swing.AbstractButton.fireActionPerformed(Unknown Source)
    at javax.swing.AbstractButton$Handler.actionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.fireActionPerformed(Unknown Source)
    at javax.swing.DefaultButtonModel.setPressed(Unknown Source)
    at javax.swing.plaf.basic.BasicButtonListener.mouseReleased(Unknown Source)
    at java.awt.Component.processMouseEvent(Unknown Source)
    at javax.swing.JComponent.processMouseEvent(Unknown Source)
    at java.awt.Component.processEvent(Unknown Source)
    at java.awt.Container.processEvent(Unknown Source)
    at java.awt.Component.dispatchEventImpl(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown Source)
    at java.awt.LightweightDispatcher.retargetMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.processMouseEvent(Unknown Source)
    at java.awt.LightweightDispatcher.dispatchEvent(Unknown Source)
    at java.awt.Container.dispatchEventImpl(Unknown Source)
    at java.awt.Window.dispatchEventImpl(Unknown Source)
    at java.awt.Component.dispatchEvent(Unknown …

我需要用0填充矩阵距离.我该怎么做？

distances <- matrix(1:25, nrow=5, ncol=5)
apply(distances, c(1, 2), function(x) 0)

public class TableModel2 extends TableModel1 { ... }

TableModel2 tableModel = new TableModel2();

boolean t1 = tableModel instanceof TableModel1;
boolean t2 = tableModel instanceof TableModel2;

在上述例子中,t1和t2是true.那么,我如何区分TableModel1和TableModel2使用instanceof？

最初,表"MyTable"已按以下方式定义:

CREATE TABLE IF NOT EXISTS `MyTable` (
  `Col1` smallint(6) NOT NULL AUTO_INCREMENT,
  `Col2` smallint(6) DEFAULT NULL,
  `Col3` varchar(20) NOT NULL,
);

如何以"Col 3"列允许为NULL的方式更新它？

有一个清单:

List<Integer[]> myList = new ArrayList<Integer[]>();

它包含一个sigle条目,但可能包含多个条目:

myList = [[2,null,1,null,null,3,6,1,1]]

我需要将此列表转换为数组Integer[][],但由于null,转换失败:

Integer[] myArr = myList.toArray(new Integer[myList.size()]);

如何解决这个问题？

编辑#1

我需要得到:

myArr = [2,null,1,null,null,3,6,1,1]

我需要从PHP中的日期时间变量中减去45分钟.

代码:

$thestime = '2012-07-27 20:40';
$datetime_from = date("Y-m-d h:i",strtotime("-45 minutes",strtotime($thestime)));
echo $datetime_from;

返回结果2012-07-27 07:55.

但应该是2012-07-27 19:55这样.我该如何解决？

如何确定Object是否为Integer？就像是:

if (obj.isInteger()) {...}