Develop Reference

Sorting strings via stream

I am doing a coding exercise where I take the the raw data from a csv file and I print it in order of lowest to highest ranked literacy rates.
For example:
Adult literacy rate, population 15+ years, female (%),United Republic of Tanzania,2015,76.08978
Adult literacy rate, population 15+ years, female (%),Zimbabwe,2015,85.28513
Adult literacy rate, population 15+ years, male (%),Honduras,2014,87.39595
Adult literacy rate, population 15+ years, male (%),Honduras,2015,88.32135
Adult literacy rate, population 15+ years, male (%),Angola,2014,82.15105
Turns into:
Niger (2015), female, 11.01572
Mali (2015), female, 22.19578
Guinea (2015), female, 22.87104
Afghanistan (2015), female, 23.87385
Central African Republic (2015), female, 24.35549
My code:
import java.io.IOException;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
public class LiteracyComparison {
public static void main(String[] args) throws IOException {
List<String> literacy = new ArrayList<>();
try (Scanner scanner = new Scanner(Paths.get("literacy.csv"))) {
while(scanner.hasNextLine()){
String row = scanner.nextLine();
String[] line = row.split(",");
line[2] = line[2].trim().substring(0, line[2].length() - 5);
line[3] = line[3].trim();
line[4] = line[4].trim();
line[5] = line[5].trim();
String l = line[3] + " (" + line[4] + "), " + line[2] + ", " + line[5];
literacy.add(l);
}
}
// right about where I get lost
literacy.stream().sorted();
}
}
Now I have converted the raw data into the correct format, it's just I am lost on how to sort it.
I am also wondering if there is a more efficient way to do this via the streams method. Please and thank you.

I took a few liberties while refactoring your code, but the idea is the same. This could be further improved but it is not intended to be a perfect solution, just something to answer your question and put you on the right track.
The main idea here is to create a nested class called LiteracyData, which stores the summary you had before as a String. However, we also want to store the literacy rate so we have something to sort by. Then you can use a Java Comparator to define your own method for comparing custom classes, in this case LiteracyData. Finally, tie it all together by calling the sort function on your List, while passing in the custom Comparator as an argument. That will sort your list. You can then print it to view the results.
import java.io.IOException;
import java.nio.file.Paths;
import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;
import java.util.Comparator;
public class LiteracyComparison {
// Define a class that stores your data
public class LiteracyData {
private String summary;
private float rate;
public LiteracyData(String summary, float rate) {
super();
this.summary = summary;
this.rate = rate;
}
}
// This is a custom Comparator we defined for sorting LiteracyData
public class LiteracySorter implements Comparator<LiteracyData>
{
#Override
public int compare(LiteracyData d1, LiteracyData d2) {
return Float.compare(d1.rate, d2.rate);
}
}
public void run() {
List<LiteracyData> literacy = new ArrayList<>();
try (Scanner scanner = new Scanner(Paths.get("literacy.csv"))) {
while(scanner.hasNextLine()){
String row = scanner.nextLine();
String[] line = row.split(",");
line[2] = line[2].trim().substring(0, line[2].length() - 5);
line[3] = line[3].trim();
line[4] = line[4].trim();
line[5] = line[5].trim();
String l = line[3] + " (" + line[4] + "), " + line[2] + ", " + line[5];
LiteracyData data = new LiteracyData(l, Float.parseFloat(line[5]));
literacy.add(data);
}
} catch (Exception e) {
System.out.println(e.getMessage());
}
// Sort the list using your custom LiteracyData comparator
literacy.sort(new LiteracySorter());
// Iterate through the list and print each item to ensure it is sorted
for(LiteracyData data : literacy) {
System.out.println(data.summary);
}
}
public static void main(String[] args) throws IOException {
LiteracyComparison comparison = new LiteracyComparison();
comparison.run();
}
}

Real time on x-axis with adjustable scale on x-axis?

I want to implement a trend graph with real time data coming continuously,for which am having time on x-axis with format "HH:MM:SS". Now my requirement is to have adjustable scale like 10min or 15min etc....And also how could i limit the time values on x-axis ?
Please help me.
Thanks!
import org.jfree.chart.ChartFactory;
import org.jfree.chart.ChartPanel;
import org.jfree.chart.JFreeChart;
import org.jfree.data.general.SeriesException;
import org.jfree.data.time.Second;
import org.jfree.data.time.TimeSeries;
import org.jfree.data.time.TimeSeriesCollection;
import org.jfree.data.xy.XYDataset;
import org.jfree.ui.ApplicationFrame;
import org.jfree.ui.RefineryUtilities;
public class TimeSeries_AWT extends ApplicationFrame
{
public TimeSeries_AWT( final String title )
{
super( title );
final XYDataset dataset = createDataset( );
final JFreeChart chart = createChart( dataset );
final ChartPanel chartPanel = new ChartPanel( chart );
chartPanel.setPreferredSize( new java.awt.Dimension( 560 , 370 ) );
chartPanel.setMouseZoomable( true , false );
setContentPane( chartPanel );
}
private XYDataset createDataset( )
{
final TimeSeries series = new TimeSeries( "Random Data" );
Second current = new Second( );
double value = 100.0;
for (int i = 0; i < 4000; i++)
{
try
{
value = value + Math.random( ) - 0.5;
series.add(current, new Double( value ) );
current = ( Second ) current.next( );
}
catch(SeriesException e )
{
System.err.println("Error adding to series");
}
}
return new TimeSeriesCollection(series);
}
private JFreeChart createChart( final XYDataset dataset )
{
return ChartFactory.createTimeSeriesChart(
"Computing Test",
"Seconds",
"Value",
dataset,
false,
false,
false);
}
public static void main( final String[ ] args )
{
final String title = "Time Series Management";
final TimeSeries_AWT demo = new TimeSeries_AWT( title );
demo.pack( );
RefineryUtilities.positionFrameRandomly( demo );
demo.setVisible( true );
}
}
If you see output, the time is constant just static not changing dynamically. and while if time updates dynamically,i want the scale or tickunits to be adjusted dynamically at runtime like for example in the output graph the scale time is 5min. but i want that to be controlled at runtime to be anything like 10min,20min,40min etc...
And another thing is in the output graph we can see 14 values on x-axis.which changes automatically when the graph is resized.but i want to control how many to be seen on the x-axis means i want to show some particular x time values on x-axis.which should also be configurable at launch of application.

Need an help to sort, Handle a tab seperated text file

Hi i have a text file(tab seperated).
I would like to open it, read it and filter the required columns just like we do in excel. Could someone help with a sample code.
I am stuck up with the concept on how to proceed further for the below steps.
Price has to sorted with DESC order before processing.
Always, First two column has to be printed in the output.
Other than the first two columns only the required column has to be printed based on the input given.
Input will be something like (Mango/purchased/top50). so it should pick only top50 "yet to buy" under "Mango" along with its respective first two columns.
Sample input file.
itemNumber Price Mango Apple Bannana
112201 purchased need to plan purchased
112202 55 yet to buy yet to buy purchased
112202 67 need to plan purchased purchased
112203 456 need to plan need to plan need to plan
112203 33 need to plan yet to buy need to plan
112204 456 need to plan yet to buy need to plan
112204 yet to buy purchased need to plan
112205 77 yet to buy purchased need to plan
112205 99 yet to buy purchased yet to buy
112206 0 yet to buy purchased yet to buy
The code is incomplete.
Here i am trying to add the heading of the file to an arraylist and adding the content to an another arraylist. Then trying to compare them using index number. Is this way correct ?
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Enumeration;
import java.util.List;
import java.util.zip.ZipEntry;
import java.util.zip.ZipFile;
public class main {
#SuppressWarnings({ "resource", "unused" })
public static void main(String[] args) throws IOException {
ZipFile zipFile = new ZipFile(
"filename.tsv.zip");
Enumeration<? extends ZipEntry> entries = zipFile.entries();
while (entries.hasMoreElements()) {
String fruit = "Mango";
String mappingstatus = "purchased";
// reading a file
ZipEntry entry = entries.nextElement();
InputStream stream = zipFile.getInputStream(entry);
InputStreamReader read = new InputStreamReader(stream);
BufferedReader br = new BufferedReader(read);
// creating a new list
List<String> heading = new ArrayList<String>();
String[] a = br.readLine().split("\t");
heading = Arrays.asList(a);
List<String> content = new ArrayList<String>();
String s;
while ((s = br.readLine()) != null) {
String[] b = br.readLine().split("\t");
content = Arrays.asList(b);
}
}
}
}

Try this
class Item implements Comparable<Item> {
int itemNumber;
int price;
String mango;
String apple;
String bannana;
public Item(int itemNumber, int price, String mango, String apple, String bannana) {
this.itemNumber = itemNumber;
this.price = price;
this.mango = mango;
this.apple = apple;
this.bannana = bannana;
}
//GETTERS
#Override
public int compareTo(Item compareItem) {
int comparePrice = ((Item) compareItem).getPrice();
//ascending order
//return this.price - comparePrice;
//descending order
return comparePrice - this.price;
}
}
public static void main(String[] args) {
List<Item> items = new ArrayList<>();
//populate the items list by creating an Item for every line you read.
//Handle null price values
Collections.sort(items);
//assuming input is some like 'Mango/purchased/top50'
String input = "Mango/purchased/top50";
String[] parts = input.split("/");
int max = Integer.parseInt(parts[2].substring(3));
List<Item> result = new ArrayList<>();
for (int i = 0; i < items.size() && result.size() < max; i++) {
Item item = items.get(i);
if ((parts[0].equals("Mango") && item.getMango().equals(parts[1]))
|| (parts[0].equals("Apple") && item.getApple().equals(parts[1]))
|| (parts[0].equals("Bannana") && item.getBannana().equals(parts[1]))) {
result.add(item);
}
}
}
Complete the commented sections and it must work. More references about sorting here: Sorting

Excel column distribution behavior during loop process, is it possible?

Using Apache POI 3.9, I want to map some values to an Excel template that looks similar to this:
Looks pretty easy, at least for the Seller table in which I can map the values from my bean without problems.
However, the issue I am facing is related to the Products table because I need to set the data from my bean for each column which makes the logic a little bit complex since during the loop process I'll need to look for the next column letter:
e.g. My first product data will be set under B7 then at C7, D7, E7, etc until the loop ends.
(Just to know, for this example template I am just showing the "Name" attribute of the product but each one has around 35 attributes in real life, that's why I am not showing the data in rows since the table won't look so friendly to the user in horizontal view).
So, my question is:
What happen If my products count is more than the total letters of the
alphabet, how can I get the right column and cell during the loop process
to set my product bean data following Excel column distribution?
With "Excel column distribution" I mean the following:
e.g. In Excel, when going to the column which contains the last letter of the alphabet "Z" then the columns continue showing AA, AB, AC, etc.
Is it possible?
This is what I've tried (using dummy data) and this will work until getting into the letter "Z" column:
Empty Excel template used in this code snippet can be downloaded at: https://www.dropbox.com/s/eo0s54o9vkqhlbl/template.xls
package com.app.test;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import org.apache.poi.hssf.usermodel.HSSFWorkbook;
import org.apache.poi.ss.usermodel.Cell;
import org.apache.poi.ss.usermodel.CellStyle;
import org.apache.poi.ss.usermodel.IndexedColors;
import org.apache.poi.ss.usermodel.Row;
import org.apache.poi.ss.usermodel.Sheet;
import org.apache.poi.ss.usermodel.Workbook;
import org.apache.poi.ss.util.CellReference;
/**
* Test class for generating Excel sheet
*/
public class ExportTest
{
public static void main(String[] args) throws IOException
{
CellReference ref;
// Load template
InputStream fis = ExportTest.class.getResourceAsStream("/template.xls");
Workbook workbook = new HSSFWorkbook(fis);
fis.close();
// Constants
final String TBL_FIRSTCOLUMN = "B"; // Starting product table column at sheet (in which the first product data will be set)
final int MAX_PRODUCTS = 25; // Max. products added to the dummy products list (this will set the last product to the "Z" column)
final int TBL_STARTROW = 7; // Starting product table row number at sheet (in which the first product data will be set)
final int TBL_ATTR_ROWS = 1; // Number of attribute rows at products table (in this case just "Name")
// Generate dummy data with seller information
LinkedHashMap<String, String> cellMap = new LinkedHashMap<String, String>();
cellMap.put("B2", "1");
cellMap.put("B3", "Company");
cellMap.put("B4", "US");
// Generate dummy data with product information
List<String> products = new ArrayList<String>();
for(int i = 0; i < MAX_PRODUCTS; ++i) {
products.add("Chocolate");
}
// Declare style for cells
CellStyle style = workbook.createCellStyle();
style.setBorderLeft(CellStyle.BORDER_THIN);
style.setLeftBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderRight(CellStyle.BORDER_THIN);
style.setRightBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderTop(CellStyle.BORDER_THIN);
style.setTopBorderColor(IndexedColors.BLACK.getIndex());
style.setBorderBottom(CellStyle.BORDER_THIN);
style.setBottomBorderColor(IndexedColors.BLACK.getIndex());
// Get template sheet
Sheet sheet = workbook.getSheetAt(0);
// Set values to "Seller" table
for(Map.Entry<String, String> entry : cellMap.entrySet()) {
ref = new CellReference(entry.getKey());
sheet.getRow(ref.getRow()).getCell(ref.getCol()).setCellValue(entry.getValue());
}
// Set values to "Products" table
for(int i = 0; i < products.size(); ++i) {
// Get product name
String name = products.get(i);
String num = String.valueOf(i + 1);
// Get char representation of the letter, this will allow me to get
// C, D, E...Z columns but then I will get a IllegalArgumentException
// if my products count exceed the alphabet letters. At this point I'll
// need to follow Excel column distribution behavior.
String nextLetter = String.valueOf((char)(TBL_FIRSTCOLUMN.charAt(0) + i));
for(int j = 0; j < TBL_ATTR_ROWS; ++j) {
// Get cell reference of B7 then C7, etc
ref = new CellReference(nextLetter + (TBL_STARTROW + j));
// Check if row/cell exists, otherwise it will throw NullPointerException when trying to get each one
Row row = sheet.getRow(ref.getRow());
if(row == null) {
row = sheet.createRow(ref.getRow());
}
Cell cell = row.getCell(ref.getCol());
if(cell == null) {
cell = row.createCell(ref.getCol());
}
// Set value and style to cell
cell.setCellValue(name + num);
cell.setCellStyle(style);
}
}
// Write workbook to file
String path = String.format("%s%s%s", System.getProperty("user.home"), System.getProperty("file.separator"), "exported.xls");
OutputStream out = new FileOutputStream(new File(path));
workbook.write(out);
out.close();
}
}
Then, If the products count exceeds the alphabet letters I will get the following exception:
Exception in thread "main" java.lang.IllegalArgumentException: Invalid
column index (-11). Allowable column range for BIFF8 is (0..255) or
('A'..'IV') at
org.apache.poi.hssf.usermodel.HSSFCell.checkBounds(HSSFCell.java:939)
at org.apache.poi.hssf.usermodel.HSSFCell.(HSSFCell.java:153)
at org.apache.poi.hssf.usermodel.HSSFRow.createCell(HSSFRow.java:148)
at org.apache.poi.hssf.usermodel.HSSFRow.createCell(HSSFRow.java:126)
at org.apache.poi.hssf.usermodel.HSSFRow.createCell(HSSFRow.java:39)
at
com.app.test.ExportTest.main(ExportTest.java:99)
(To replicate this try using MAX_PRODUCTS = 26, NOT 27 - alphabet count - since we are starting at B column on Excel sheet).
Any help will be appreciated, thanks!

You call a utility method in Apache POI -- CellReference.convertNumToColString to map your column number into an Excel column designation.
Takes in a 0-based base-10 column and returns a ALPHA-26 representation. eg column #3 -> D
Since you're starting with column "B" (1), add 1 to i first.
String nextLetter = String.valueOf(CellReference.convertNumToColString(i + 1));

Predicting data created on-the-fly in WEKA using a premade model file

I want to create a WEKA Java program that reads a group of newly created data that will be fed to a premade model from the GUI version.
Here is the program:
import java.util.ArrayList;
import weka.classifiers.Classifier;
import weka.core.Attribute;
import weka.core.DenseInstance;
import weka.core.Instances;
import weka.core.Utils;
public class UseModelWithData {
public static void main(String[] args) throws Exception {
// load model
String rootPath = "G:/";
Classifier classifier = (Classifier) weka.core.SerializationHelper.read(rootPath+"j48.model");
// create instances
Attribute attr1 = new Attribute("age");
Attribute attr2 = new Attribute("menopause");
Attribute attr3 = new Attribute("tumor-size");
Attribute attr4 = new Attribute("inv-nodes");
Attribute attr5 = new Attribute("node-caps");
Attribute attr6 = new Attribute("deg-malig");
Attribute attr7 = new Attribute("breast");
Attribute attr8 = new Attribute("breast-quad");
Attribute attr9 = new Attribute("irradiat");
Attribute attr10 = new Attribute("Class");
ArrayList<Attribute> attributes = new ArrayList<Attribute>();
attributes.add(attr1);
attributes.add(attr2);
attributes.add(attr3);
attributes.add(attr4);
attributes.add(attr5);
attributes.add(attr6);
attributes.add(attr7);
attributes.add(attr8);
attributes.add(attr9);
attributes.add(attr10);
// predict instance class values
Instances testing = new Instances("Test dataset", attributes, 0);
// add data
double[] values = new double[testing.numAttributes()];
values[0] = testing.attribute(0).addStringValue("60-69");
values[1] = testing.attribute(1).addStringValue("ge40");
values[2] = testing.attribute(2).addStringValue("10-14");
values[3] = testing.attribute(3).addStringValue("15-17");
values[4] = testing.attribute(4).addStringValue("yes");
values[5] = testing.attribute(5).addStringValue("2");
values[6] = testing.attribute(6).addStringValue("right");
values[7] = testing.attribute(7).addStringValue("right_up");
values[8] = testing.attribute(0).addStringValue("yes");
values[9] = Utils.missingValue();
// add data to instance
testing.add(new DenseInstance(1.0, values));
// instance row to predict
int index = 10;
// perform prediction
double myValue = classifier.classifyInstance(testing.instance(10));
// get the name of class value
String prediction = testing.classAttribute().value((int) myValue);
System.out.println("The predicted value of the instance ["
+ Integer.toString(index) + "]: " + prediction);
}
}
My references include:
Using a premade WEKA model in Java
the WEKA Manual provided in the 3.7.10 version - 17.3 Creating datasets in memory
Creating a single instance for classification in WEKA
So far the part where I create a new Instance inside the script causes the following error:
Exception in thread "main" java.lang.IndexOutOfBoundsException: Index: 10, Size: 1
in the line
double myValue = classifier.classifyInstance(testing.instance(10));
I just want to use a latest row of instance values to a premade WEKA model. How do I solve this?
Resources
Program file
Arff file
j48.model

You have the error because you are trying to access the 11th instance and have only created one.
If you always want to access the last instance you might try the following:
double myValue = classifier.classifyInstance(testing.lastInstance());
Additionally, I don't believe that you are creating the instances you hope for. After looking at your provided ".arff" file, which I believe you are trying to mimic, I think you should proceed making instances as follows:
FastVector atts;
FastVector attAge;
Instances testing;
double[] vals;
// 1. set up attributes
atts = new FastVector();
//age
attAge = new FastVector();
attAge.addElement("10-19");
attAge.addElement("20-29");
attAge.addElement("30-39");
attAge.addElement("40-49");
attAge.addElement("50-59");
attAge.addElement("60-69");
attAge.addElement("70-79");
attAge.addElement("80-89");
attAge.addElement("90-99");
atts.addElement(new Attribute("age", attAge));
// 2. create Instances object
testing = new Instances("breast-cancer", atts, 0);
// 3. fill with data
vals = new double[testing.numAttributes()];
vals[0] = attAge.indexOf("10-19");
testing.add(new DenseInstance(1.0, vals));
// 4. output data
System.out.println(testing);
Of course I did not create the whole dataset, but the technique would be the same.