Java Read CSV line by line JS - Printable Version

[Java] Read CSV line by line JS - Printable Version

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Read CSV line by line JS - Raitz - Nov 3, 2017

I need to read data separated by commas line by line. The csv files are in /data/name.js. Each line has 6 columns, ideally I would like to take the data straight from the file and calculate the maximum and minimum of the 4th and 5th columns which are numbers.

RE: Read CSV line by line JS - ZeratulTheWizard - Nov 3, 2017

Do you want to read this in Java or JavaScript since the file is in JS?

RE: Read CSV line by line JS - _wind - Nov 3, 2017

Basically, you would read the file like any other .txt file and then split each line by commas to create a string array.
Here's a quick demo I wrote that should work:

Code 
import java.io.File;

import java.io.IOException;

import java.nio.charset.StandardCharsets;

import java.nio.file.Files;

import java.util.List;

public class test {

    public static void main(String[] args){

        File file = new File("data.csv"); 

        List<String> lines;

        try {

            lines = Files.readAllLines(file.toPath(), StandardCharsets.UTF_8);

            for (String line : lines) { 

               String[] array = line.split(","); 

               int num1 = Integer.parseInt(array[3]);

               int num2 = Integer.parseInt(array[4]);

               if(num1 > num2){

                   //do something

               }

            }

        } catch (IOException e) {

            e.printStackTrace();

        } 

    }

}

Code taken from https://stackoverflow.com/questions/45101192/how-to-read-specific-columns-in-csv-file-java

RE: Read CSV line by line JS - Raitz - Nov 3, 2017

I need to read the file in JS. I think using D3 will work but I have over 50 csv files in the data folder and need to read data from each of them.

RE: Read CSV line by line JS - _wind - Nov 3, 2017

I'm not sure I'm getting what you're trying to accomplish. Do you have your 50 comma-separated values compiled into a file with a .js extension or do you want to use JavaScript to read 50 different .csv files?

RE: Read CSV line by line JS - Raitz - Nov 4, 2017

(Nov 3, 2017 09:23 PM)Polunom Wrote: I'm not sure I'm getting what you're trying to accomplish. Do you have your 50 comma-separated values compiled into a file with a .js extension or do you want to use JavaScript to read 50 different .csv files?

I have 55 different .csv files, all with 6 columns. Im trying to read those using javascript.

RE: Read CSV line by line JS - _wind - Nov 4, 2017

I don't think it's possible with JavaScript for security purposes. Or maybe you can; I don't know. I would, however, use Node.js or PHP.

Why would you ever need to read 50 .csv files in JavaScript though? Couldn't you parse it in Java and output whatever you need?

RE: Read CSV line by line JS - ZeratulTheWizard - Nov 4, 2017

I agree with Polumon. Unless you're working with a framework for a server, there isn't really a good way to access a local file with JS. If the file can be downloaded via an XHR request, that seems more reasonable.