CODEWITHSUNDEEP
javaarrayscsvopencsv
S Singh
S Singh

Reputation: 1473

Need to delete empty columns in csv

I have created CSV file using Open CSV library using some run time data coming from different datasource.

Now I am looking a lot of empty columns which doesn't have value in column cells and so I want to delete that programmatically.

Approach I am currently trying to implement is, get first CSV data in String 2 dimensional array and iterate it vertically and do something to delete empty columns!

Is any other better approach I can follow? Pls suggest!

Regards

//edited

Code for writing in CSV using OpenCSV library:

public static void writeDataToCSV(CSVWriter writer, String[][] csvData){
    List<String[]> csvDataList = new ArrayList<String[]>();
    for (String[] rowData : csvData) {
        csvDataList.add(rowData);
    }
    writer.writeAll(csvDataList);
}

Upvotes: 3

Views: 5212

Answers (2)

Konstantin Tarashchanskiy
Konstantin Tarashchanskiy

Reputation: 2800

Did not actually run this, so some errors may exist, but the rough skeleton should be:

int height;  //How many rows
int width;  //How many columns per row

Set<Integer> emptyCols = new HashSet<Integers>();  //Columns that are empty

for (int x = 0; x < width; x++) { //Look at each column
  boolean empty = true; //We have yet to find an item in this column
  for (int y = 0; y < height; y++) {
    if (!data[y][x].isEmpty()) {  //This column is not empty, we can move on
      empty = false;
      break;
    }
  }

  if (empty) {
    emptyCols.add(x);
  }
}

for (int y = 0; y < height; y++) {
  for (int x = 0; x < width; x++) {
    if (!emptyCols.contains(x)) {
      //write out data[y][x]
    }
  }
  //Terminate row
}

Upvotes: 0

Ascalonian
Ascalonian

Reputation: 15174

So in the provided String[], you know what index of the column you need to remove, correct? If so, you can do this:

for (String[] rowData : csvData) {
    // Convert the String[] to an ArrayList to be able to easily remove the specific column
    ArrayList<String> rowArray = new ArrayList<String>(Arrays.asList(rowData));

    // Remove that specific column value
    rowArray.remove(<index of column>);

    // Convert the ArrayList back into an array so it can be written to the CSV
    String[] dataToWrite = rowArray.toArray(new String[rowArray.size()]);

    // Add it to the ArrayList of values to be written
    csvDataList.add(dataToWrite);
}

Upvotes: 1

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