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I have a .csv file that is formated like this:
ID,date,itemName
456,1-4-2020,Lemon
345,1-3-2020,Bacon
345,1-4-2020,Sausage
123,1-1-2020,Apple
123,1-2-2020,Pineapple
234,1-2-2020,Beer
345,1-4-2020,Cheese
I have already implemented the algorithm to go through the file, scan for the first number and sort it in a descending order and make a new output:
123,1-1-2020,Apple
123,1-2-2020,Pineapple
234,1-2-2020,Beer
345,1-3-2020,Bacon
345,1-4-2020,Cheese
345,1-4-2020,Sausage
456,1-4-2020,Lemon
My question is, how do I implement my algorithm to make an output that counts the duplicate first number entries and reformat it to make it look like this...
123,1-1-2020,1,Apple
123,1-2-2020,1,Pineapple
234,1-2-2020,1,Beer
345,1-3-2020,1,Bacon
345,1-4-2020,2,Cheese,Sausage
456,1-4-2020,1,Lemon
...so that it counts the number of occurrence for each ID, denote it with the number of times, and if the date of that ID is also the same, combine the item names to the same line. Below is my source code (each line in the .csv is made into an object named 'receipt' that has ID, date, and name with their respective get() methods):
public class ReadFile {
private static List<Receipt> readFile() {
List<Receipt> receipts = new ArrayList<>();
try {
BufferedReader reader = new BufferedReader(new FileReader("dataset.csv"));
// Move past the first title line
reader.readLine();
String line = reader.readLine();
// Start reading from second line till EOF, split each string at ","
while (line != null) {
String[] attributes = line.split(",");
Receipt attribute = getAttributes(attributes);
receipts.add(attribute);
line = reader.readLine();
}
reader.close();
} catch (IOException e) {
e.printStackTrace();
}
return receipts;
}
private static Receipt getAttributes(String[] attributes) {
// Get ID located before the first ","
long memberNumber = Long.parseLong(attributes[0]);
// Get date located after the first ","
String date = attributes[1];
// Get name located after the second ","
String name = attributes[2];
return new Receipt(memberNumber, date, name);
}
// Parse the data into new file after sorting
private static void parse(List<Receipt> receipts) {
PrintWriter output = null;
try {
output = new PrintWriter("output.txt");
} catch (FileNotFoundException e) {
e.printStackTrace();
}
// For each receipts, assert the text output stream is not null, print line.
for (Receipt p : receipts) {
assert output != null;
output.println(p.getMemberNumber() + "," + p.getDate() + "," + p.getName());
}
assert output != null;
output.close();
}
// Main method, accept input file, sort and parse
public static void main(String[] args) {
List<Receipt> receipts = readFile();
QuickSort q = new QuickSort();
q.quickSort(receipts);
parse(receipts);
}
}
The easiest way is to use a map.
Sample data from your file.
String[] lines = {
"123,1-1-2020,Apple",
"123,1-2-2020,Pineapple",
"234,1-2-2020,Beer",
"345,1-3-2020,Bacon",
"345,1-4-2020,Cheese",
"345,1-4-2020,Sausage",
"456,1-4-2020,Lemon"};
Create a map
as you read the lines, split them and add them to the map using the compute method. This will put the line in if the key (number and date) doesn't exist. Otherwise it simply appends the last item to the existing entry.
the file does not have to be sorted but the values will be added to the end as they are encountered.
Map<String, String> map = new LinkedHashMap<>();
for (String line : lines) {
String[] vals = line.split(",");
// if v is null, add the line
// if v exists, take the existing line and append the last value
map.compute(vals[0]+vals[1], (k,v)->v == null ? line : v +","+vals[2]);
}
for (String line : map.values()) {
String[] fields = line.split(",",3);
int count = fields[2].split(",").length;
System.out.printf("%s,%s,%s,%s%n", fields[0],fields[1],count,fields[2]);
}
For this sample run prints
123,1-1-2020,1,Apple
123,1-2-2020,1,Pineapple
234,1-2-2020,1,Beer
345,1-3-2020,1,Bacon
345,1-4-2020,2,Cheese,Sausage
456,1-4-2020,1,Lemon
I'm currently working on a program that reads in a preset text file and then manipulates the data in various ways. I've got the data manipulation to work with some dummy data but I still need to get the text file read in correctly.
The test file looks like this for 120 lines:
Aberdeen,Scotland,57,9,N,2,9,W,5:00,p.m. Adelaide,Australia,34,55,S,138,36,E,2:30,a.m. Algiers,Algeria,36,50,N,3,0,E,6:00,p.m.(etc etc)
So each of these needs to be read into its own array, in order String[] CityName,String[] Country,int[] LatDeg,int[] LatMin,String[] NorthSouth,int[] LongDeg,int LongMin,String[] EastWest,int[] Time.String[] AMPM
So the problem is that while I'm reasonably comfortable with buffered readers, designing this particular function has proven difficult. In fact, I've been drawing a blank for the past few hours. It seems like it would need multiple loops and counters but I can't figure out the precisely how.
I am assuming that you have one city per line type of file structure. If it is not, it will require a bit of tweaking in the following solution:
I will do the following way if I am more comfortable with BufferReader as you say:
List<List<String>> addresses = new ArrayList<List<String>>();
try(BufferedReader br = new BufferedReader(new FileReader(file))) {
for(String line; (line = br.readLine()) != null; ) {
addresses.add(line.split(","));
}
}
Later, let's say you want to retrieve the country information of say 'Adelaid', you can try the following:
for (List<String> cityInfo : addresses) {
if("Adelaid".equals(cityInfo.get(0)) {
country = cityInfo.get(1);
}
}
Instead of creating different arrays (like String[] CityName,String[] Country, etc.,), try using a Domain Object.
Here, you can have a Domain object or Custom class Location with attributes
public class Location
{
private String cityName;
private String country;
private String latDeg;
etc
getters();
setters();
}`
Then you can write a file reader, each line item in the file will be a Location. So result will have
Location[] locations;
or
List locations;`
To carry out this task I should think the first thing you want to do is establish how many lines of data actually exist within the data file. You say it is 120 lines but what if it happens that it will be more or less? We would want to know exactly what it is so as to properly initialize all our different Arrays. We can use a simple method to accomplish this, let's call it the getFileLinesCount() method which will ulitmately return a Integer value that would be the number of text lines the data file holds:
private int getFileLinesCount(final String filePath) {
int lines = 0;
try{
File file =new File(filePath);
if(file.exists()){
FileReader fr = new FileReader(file);
try (LineNumberReader lnr = new LineNumberReader(fr)) {
while (lnr.readLine() != null){ lines++; }
}
}
else {
throw new IllegalArgumentException("GetFileLinesCount() Method Error!\n"
+ "The supplied file path does not exist!\n(" + filePath + ")");
}
}
catch(IOException e){ e.printStackTrace(); }
return lines;
}
Place this method somewhere within your main class. Now you need to Declare and initialize all your Arrays:
String filePath = "C:\\My Files\\MyDataFile.txt";
int lines = getFileLinesCount(filePath);
String[] CityName = new String[lines];
String[] Country = new String[lines];
int[] LatDeg = new int[lines];
int[] LatMin = new int[lines];
String[] NorthSouth = new String[lines];
int[] LongDeg = new int[lines];
int[] LongMin = new int[lines];
String[] EastWest = new String[lines];
int[] Time = new int[lines];
String[] AMPM = new String[lines];
Now to fill up all those Arrays:
public static void main(String args[]) {
loadUpArrays();
// Do whatever you want to do
// with all those Arrays.....
}
private void loadUpArrays() {
// Read in the data file.
try (BufferedReader br = new BufferedReader(new FileReader(filePath))) {
String sCurrentLine;
int x = 0;
// Read in one line at a time and Fill the Arrays...
while ((sCurrentLine = br.readLine()) != null) {
// Split each line read into an array upon itself.
String[] fileLine = sCurrentLine.split(",");
// Fill our required Arrays...
CityName[x] = fileLine[0];
Country[x] = fileLine[1];
LatDeg[x] = Integer.parseInt(fileLine[2]);
LatMin[x] = Integer.parseInt(fileLine[3]);
NorthSouth[x] = fileLine[4];
LongDeg[x] = Integer.parseInt(fileLine[5]);
LongMin[x] = Integer.parseInt(fileLine[6]);
EastWest[x] = fileLine[7];
Time[x] = Integer.parseInt(fileLine[8]);
AMPM[x] = fileLine[9];
x++;
}
br.close();
}
catch (IOException ex) { ex.printStackTrace(); }
}
Now, I haven't tested this, I just quickly punched it out but I think you can get the jest of it.
EDIT:
As #Mad Physicist has so graciously pointed out within his comment below, a List can be used to eliminate the need to count file lines therefore eliminating the need to read the data file twice. All the file lines can be placed into the List and the number of valid file lines can be determined by the size of the List. Filling of your desired arrays can now also be achieved by iterating through the List elements and processing the data accordingly. Everything can be achieved with a single method we'll call fillArrays(). Your Arrays declaration will be a little different however:
String[] CityName;
String[] Country;
int[] LatDeg;
int[] LatMin;
String[] NorthSouth;
int[] LongDeg;
int[] LongMin;
String[] EastWest;
String[] Time;
String[] AMPM;
public static void main(String args[]) {
fillArrays("C:\\My Files\\MyDataFile.txt");
// Whatever you want to do with all
// those Arrays...
}
private void fillArrays(final String filePath) {
List<String> fileLinesList = new ArrayList<>();
try{
File file = new File(filePath);
if(file.exists()){
try (BufferedReader br = new BufferedReader(new FileReader(file))) {
String strg;
while((strg = br.readLine()) != null){
// Make sure there is no blank line. If not
// then add line to List.
if (!strg.equals("")) { fileLinesList.add(strg); }
}
br.close();
}
}
else {
throw new IllegalArgumentException("GetFileLinesCount() Method Error!\n"
+ "The supplied file path does not exist!\n(" + filePath + ")");
}
// Initialize all the Arrays...
int lines = fileLinesList.size();
CityName = new String[lines];
Country = new String[lines];
LatDeg = new int[lines];
LatMin = new int[lines];
NorthSouth = new String[lines];
LongDeg = new int[lines];
LongMin = new int[lines];
EastWest = new String[lines];
Time = new String[lines];
AMPM = new String[lines];
// Fill all the Arrays...
for (int i = 0; i < fileLinesList.size(); i++) {
String[] lineArray = fileLinesList.get(i).split(",");
CityName[i] = lineArray[0];
Country[i] = lineArray[1];
LatDeg[i] = Integer.parseInt(lineArray[2]);
LatMin[i] = Integer.parseInt(lineArray[3]);
NorthSouth[i] = lineArray[4];
LongDeg[i] = Integer.parseInt(lineArray[5]);
LongMin[i] = Integer.parseInt(lineArray[6]);
EastWest[i] = lineArray[7];
Time[i] = lineArray[8];
AMPM[i] = lineArray[9];
}
}
catch(IOException e){ e.printStackTrace(); }
}
On another note...your Time Array can not be Integer since in data, what is considered the time contains a colon (:) which is a alpha character therefore (in case you haven't noticed) I have changed its declaration to String[]
I am trying to complete a little program.
I've got a text file (.txt) to store different data on objects that i've got.
The structure of the file is the next (exemples data.txt) :
Sedane
2005
195000
Diesel
Blue
SUV
2013
34000
Fuel
Black
Each object is made true a class that i've build called Cars.
So the 1 line is the type of car, the 2nd the year of built, the 3rd line is the milage, the 4th is the type of fuel, and the 5th line is the color of the car.
So basicly i need to open the file, and load the data into the memory when i execute my program into an array with object in it.
I'm ok to open the file but i'm blocked when it comes to reading the data and putting it in an array.
The array size is 2 for this exemple, but if i have more entries in the file it's going to adapt it's size when loading at the startup of the program.
Here's what i've got unti now (for my code ...)
public static void loadCars () {
FileReader fopen;
BufferedReader opened;
String line;
try {
fEntree = new FileReader( "data.txt" );
opened = new BufferedReader( fopen );
while ( opened.ready() ) {
line = opened.readLine();
// Don't know what to do here ????
}
opened.close();
} catch ( IOException e ) {
System.out.println( "File doesn't exist !" );
}
}
Someting like this will do the trick. I'm adding the file contents line by line to an Arraylist instead of an array though. This way you don't have to know how big your array needs to be before hand. Plus you can always change it to an array later.
public ArrayList<String> readFileToMemory(String filepath)
{
in = new BufferedReader(new FileReader( "data.txt" ));
String currentLine = null;
ArrayList<String> fileContents = new ArrayList<String>();
try
{
while((currentLine = in.readLine()) != null)
{
fileContents.add(currentLine);
}
}
catch(IOException e)
{
e.printStackTrace();
}
finally
{
try
{
in.close();
}
catch(IOException e)
{
e.printStackTrace();
}
}
return fileContents;
}
LineNumberReader lnr = new LineNumberReader(new FileReader(new File("File1")));
lnr.skip(Long.MAX_VALUE);
long length = lnr.getLineNumber();
lnr.close();
in = new BufferedReader(new FileReader( "data.txt" ));
Car[] cars= new Car[length/5];
String currentLine;
int i=0;
for(int i=0;i<length/5;i+=5) {
String name = in.readLine();
String year = in.readLine();
String miles = in.readLine();
String gas = in.readLine();
String color = in.readLine();
cars[i] = new Car(name,year,miles,gas,color);
}
You'll have to handle exceptions too, surround stuff in try catch structures.
You can look at my solution here below (I also corrected/simplified some problems with the variables for reading the file, anyway this was not the main topic):
public static void loadCars() {
FileReader fopen;
BufferedReader opened;
String line;
ArrayList<Car> carList = new ArrayList<Car>();
try {
fopen = new FileReader("data.txt");
opened = new BufferedReader(fopen);
int nFields = 5; // we have 5 fields in the Car class
String[] fields = new String[nFields]; // to temporary store fields values read line by line
int lineCounter = 0;
while ((line = opened.readLine()) != null) {
fields[lineCounter] = line;
lineCounter++;
if ((lineCounter) % nFields == 0) { //it means we have all 5 fields values for a car
carList.add(new Car(fields)); //therefore we create a new car and we add it to the list of cars
}
}
opened.close();
} catch (IOException e) {
System.out.println("File doesn't exist !");
}
}
Basically we use an ArrayList to store all the cars, and we read the file, waiting to have all the fields values in order to create the Car object. I store the fields values in an array of Strings: I don't know how you implemented the Car class, but maybe it is useful to create a constructor that takes as parameter an array of strings, so it can set the fields, for instance:
class Car {
private String type;
private String year;
private String milage;
private String fuel;
private String color;
public Car(String[] fields) {
type=fields[0];
year=fields[0];
milage=fields[0];
fuel=fields[0];
type=fields[0];
}
}
But I've to say that probably this is a little 'too static'.
For simplicity I assumed that all your fields are of String type, but probably fields like 'year' or 'milage' might be of int type. In this case you can use array of Object[] (instead of String[]), and then cast the value with the right type.
I hope this may help you.
I am having some trouble pulling values from a CSV file for android app that I am working on. The CSV file takes the following format:
Acton Town (District),Acton Town (Piccadilly),2.00
Aldgate (Circle),Aldgate (Metropolitan),4.00
Aldgate East (District),Aldgate East (Hammersmith And City),2.00
I am trying to import it into my java class using the following method:
public ArrayList<Connection> importConnections(){
try
{
//gets the lines.txt file from assets
in = this.getAssets().open("connections.csv");
Scanner scan = new Scanner(in);
TextView lineData = (TextView)findViewById(R.id.displayLine);
String connection = null;
String startingStation = null;
String endingStation = null;
Float duration = 0;
do
{
connection = scan.nextLine();
String delimiter = ",\n";
StringTokenizer tokens = new StringTokenizer(connection, delimiter);
startingStation = tokens.nextToken();
endingStation = tokens.nextToken();
duration = Float.parseFloat(tokens.nextToken());
connections.add(startStation, endStation, duration);
}
while(scan.hasNext());
//for testing purposes
lineData.setText(endingStation);
}
catch (IOException e)
{
// TODO Auto-generated catch block
e.printStackTrace();
}
return connections;
}
If I run this, the app will crash and I can't figure out why. If I set lineData.setText(endingStation) as lineData.setText(connection), it will display the entire row e.g:
Acton Town (District),Acton Town (Piccadilly),2.00
If I comment out the
duration = Float.parseFloat(tokens.nextToken());
it will run the method. Can anyone find any fault with this method?
You could try using OpenCSV http://opencsv.sourceforge.net/
It is pretty simple to use and returns an array of each row.
CSVReader reader = new CSVReader(new FileReader(<filepath>));
String[] temp;
int NUM = #; //number of rows in csv, or insert code to read through file until null.
for(int i = 0; i < NUM; i++)
{
temp = reader.readNext(); //read next line into temp
}
System.out.println(temp[0]); //Acton Town (District)
System.out.println(temp[1]); //Acton Town (Piccadilly)
System.out.println(temp[2]); //2.00 (string)
reader.close();
Like I said, it is easy to use and prevents you from having to parse out the string on your own.
The code I have produced is meant to provide functionality of reading a text file line by line, saving each line into an array. It seems to read in each line correctly but when I use the printProps() method it only displays one...
Code is only saving one line of a text file to the array, what's wrong with my code?
/*reading in each line of text from text file and passing it to the processProperty() method.*/
Public void readProperties(String filename) {
try {
BufferedReader reader = new BufferedReader(new FileReader(filename));
int i = 0;
String line;
line = reader.readLine();
while (line != null && !line.equals("")) {
i++;
processProperty(line);
line = reader.readLine();
}
System.out.println("" + i + " properties read");
} catch (Exception e) {
System.err.println(e.getMessage());
e.printStackTrace();
}
}
/*Breaks up the line of text in order to save the value to an array (at this point it only saves one line to the array). org.newProp(newProp) passes the new property to the Organize class where it saves it to an array.
public void processProperty(String line) {
org = new Organize();
int id = nextPropertyID;
nextPropertyID++;
String[] parts = line.split(":");
int propNo = Integer.parseInt(parts[0]);
String postcode = parts[1];
String type = parts[2];
int bedrooms = Integer.parseInt(parts[3]);
int year = Integer.parseInt(parts[4]);
int rental = Integer.parseInt(parts[5]);
Landlord landlord = theLandlord;
Tenant tenant = null;
org.propUniqueCheck(id);
propNoCheck(propNo, postcode);
postcodeCheck(postcode,propNo);
typeCheck(postcode, propNo, type);
bedroomsCheck(bedrooms, postcode, propNo);
yearCheck(propNo, postcode, year);
System.out.println("Creating property " + id);
Property newProp = new Property(id, propNo, postcode, type, bedrooms, year,
rental, landlord, tenant);
org.newProp(newProp);
org.printProps();
}
/*From here down it is the code to save the value to the array*/
public Organize() {
props = new ArrayList<Property>();
PTs = new ArrayList<PotentialTenant>();
waitingList = new LinkedList<String>();
//myList.add(new prop(Property.toString()));
}
public void newProp(Property p)
{
props.add(p);
}
I have actively been seeking help in my seminar with this problem and I can't seem to find a solution, any advice would be very much appreciated!
In processProperty you are instantiating a new Organize object. Therefore, each Property (which you create for each row) is ending up in a different ArrayList (as the first element).
One solution would be to instantiate one Organize object before you start your loop and then pass this into your processProperty method as a parameter.
When one line in your text file is an empty String, your while-loop will break.
This is the right way to implement the loop:
String line = "";
while ((line = reader.readLine()) != null) {
// your code here
}
In processProperty you are instantiating a new Organize object. Therefore, each Property (which you create for each row) is ending up in a different ArrayList (as the first element).
One solution would be to instantiate one Organize object before you start your loop and then pass this into your processProperty method as a parameter.
String line = "";
while ((line = reader.readLine()) != null) {
// your code here
}