POI / Excel : applying formulas in a “relative” wa

Question

I'm using Apache's POI to manipulate Excel (.xls) files with Java.

I'm trying to create a new cell whom content is the result of a formula as if the user had copied/pasted the formula (what i call the "relative" way, as opposite to "absolute").

To make myself clearer, here is a simple example : Cell A1 contains "1",B1 contains "2", A2 contains "3", B2 contains "4". Cell A3 contains the following formula "=A1+B1". If I copy the formula to the A4 cell under excel, it becomes "=A2+B2" : excel is adapting the content of the formula dynamically.

Unfortunately I cannot get the same result programatically. The only solution I found is to tokenize the formula and do the dirty work myself, but I really doubt that this is supposed to be done that way. I was not able to find what I'm looking for in the guides or in the API.

Is there an easier way to solve this problem ? If it's the case, can you please point me in the right direction ?

Best regards,

Nils

Answer 1

Another way to copy formula relatively, tested with poi 3.12

public static void copyCellFormula(Workbook workbook, int sheetIndex, int rowIndex, int sourceColumnIndex, int destinationColumnIndex){
    XSSFEvaluationWorkbook formulaParsingWorkbook = XSSFEvaluationWorkbook.create((XSSFWorkbook) workbook);
    SharedFormula sharedFormula = new SharedFormula(SpreadsheetVersion.EXCEL2007);
    Sheet sheet = workbook.getSheetAt(sheetIndex);
    Row lookupRow = sheet.getRow(rowIndex);
    Cell sourceCell = lookupRow.getCell(sourceColumnIndex);
    Ptg[] sharedFormulaPtg = FormulaParser.parse(sourceCell.getCellFormula(), formulaParsingWorkbook, FormulaType.CELL, sheetIndex);
    Ptg[] convertedFormulaPtg = sharedFormula.convertSharedFormulas(sharedFormulaPtg, 0, 1);
    Cell destinationCell = lookupRow.createCell(destinationColumnIndex);
    destinationCell.setCellFormula(FormulaRenderer.toFormulaString(formulaParsingWorkbook, convertedFormulaPtg));
}

Update shared formula as needed:

sharedFormula.convertSharedFormulas(sharedFormulaPtg, rowIndexOffset, columnIndexOffset);

As of poi 3.12, SharedFormula doesn't support cell reference/formula from other sheets (='Sheet1'!A1). Here's an update to SharedFormula:

public class SharedFormula {

    private final int _columnWrappingMask;
    private final int _rowWrappingMask;

    public SharedFormula(SpreadsheetVersion ssVersion) {
        this._columnWrappingMask = ssVersion.getLastColumnIndex();
        this._rowWrappingMask = ssVersion.getLastRowIndex();
    }

    public Ptg[] convertSharedFormulas(Ptg[] ptgs, int formulaRow, int formulaColumn) {
        Ptg[] newPtgStack = new Ptg[ptgs.length];

        RefPtgBase areaNPtg = null;
        AreaPtgBase var9 = null;
        Object ptg = null;
        byte originalOperandClass = 0;
        for(int k = 0; k < ptgs.length; ++k) {
            ptg = ptgs[k];
            originalOperandClass = -1;
            if(!((Ptg)ptg).isBaseToken()) {
                originalOperandClass = ((Ptg)ptg).getPtgClass();
            }

            if(ptg instanceof RefPtgBase) {
                if(ptg instanceof Ref3DPxg) {
                    areaNPtg = (Ref3DPxg)ptg;
                    this.fixupRefRelativeRowAndColumn(areaNPtg, formulaRow, formulaColumn);
                    ptg = areaNPtg;
                }else if(ptg instanceof Ref3DPtg) {
                    areaNPtg = (Ref3DPtg)ptg;
                    this.fixupRefRelativeRowAndColumn(areaNPtg, formulaRow, formulaColumn);
                    ptg = areaNPtg;
                }else {
                    areaNPtg = (RefPtgBase)ptg;
                    ptg = new RefPtg(this.fixupRelativeRow(formulaRow, areaNPtg.getRow(), areaNPtg.isRowRelative()), this.fixupRelativeColumn(formulaColumn, areaNPtg.getColumn(), areaNPtg.isColRelative()), areaNPtg.isRowRelative(), areaNPtg.isColRelative());
                }
                ((Ptg)ptg).setClass(originalOperandClass);
            }else if(ptg instanceof AreaPtgBase) {
                if(ptg instanceof  Area3DPxg) {
                    var9 = (Area3DPxg)ptg;
                    this.fixupAreaRelativeRowAndColumn(var9, formulaRow, formulaColumn);
                    ptg = var9;
                }else if(ptg instanceof  Area3DPxg) {
                    var9 = (Area3DPtg)ptg;
                    this.fixupAreaRelativeRowAndColumn(var9, formulaRow, formulaColumn);
                    ptg = var9;
                }else {
                    var9 = (AreaPtgBase)ptg;
                    ptg = new AreaPtg(this.fixupRelativeRow(formulaRow, var9.getFirstRow(), var9.isFirstRowRelative()), this.fixupRelativeRow(formulaRow, var9.getLastRow(), var9.isLastRowRelative()), this.fixupRelativeColumn(formulaColumn, var9.getFirstColumn(), var9.isFirstColRelative()), this.fixupRelativeColumn(formulaColumn, var9.getLastColumn(), var9.isLastColRelative()), var9.isFirstRowRelative(), var9.isLastRowRelative(), var9.isFirstColRelative(), var9.isLastColRelative());
                }
                ((Ptg)ptg).setClass(originalOperandClass);
            }else if(ptg instanceof OperandPtg) {
                ptg = ((OperandPtg)ptg).copy();
            }

            newPtgStack[k] = (Ptg)ptg;
        }

        return newPtgStack;
    }

    protected void fixupRefRelativeRowAndColumn(RefPtgBase areaNPtg, int formulaRow, int formulaColumn){
        areaNPtg.setRow(this.fixupRelativeRow(formulaRow, areaNPtg.getRow(), areaNPtg.isRowRelative()));
        areaNPtg.setColumn(this.fixupRelativeColumn(formulaColumn, areaNPtg.getColumn(), areaNPtg.isColRelative()));
        areaNPtg.setRowRelative(areaNPtg.isRowRelative());
        areaNPtg.setColRelative(areaNPtg.isColRelative());
    }

    protected void fixupAreaRelativeRowAndColumn(AreaPtgBase var9, int formulaRow, int formulaColumn){
        var9.setFirstRow(this.fixupRelativeRow(formulaRow, var9.getFirstRow(), var9.isFirstRowRelative()));
        var9.setLastRow(this.fixupRelativeRow(formulaRow, var9.getLastRow(), var9.isLastRowRelative()));
        var9.setFirstColumn(this.fixupRelativeColumn(formulaColumn, var9.getFirstColumn(), var9.isFirstColRelative()));
        var9.setLastColumn(this.fixupRelativeColumn(formulaColumn, var9.getLastColumn(), var9.isLastColRelative()));
        var9.setFirstRowRelative(var9.isFirstRowRelative());
        var9.setLastRowRelative(var9.isLastRowRelative());
        var9.setFirstColRelative(var9.isFirstColRelative());
        var9.setLastColRelative(var9.isLastColRelative());
    }

    protected int fixupRelativeColumn(int currentcolumn, int column, boolean relative) {
        return relative?column + currentcolumn & this._columnWrappingMask:column;
    }

    protected int fixupRelativeRow(int currentrow, int row, boolean relative) {
        return relative?row + currentrow & this._rowWrappingMask:row;
    }

}

Answer 2

I looked inside FormulaEvaluator class and found some POI internal classes that can do the work for us.

FormulaParser, which parses String to array of "parse things":

String formula = cell.getCellFormula();
XSSFEvaluationWorkbook workbookWrapper = 
             XSSFEvaluationWorkbook.create((XSSFWorkbook) workbook);  
/* parse formula */
Ptg[] ptgs = FormulaParser.parse(formula, workbookWrapper, 
             FormulaType.CELL, 0 /*sheet index*/ );

ptgs is now our formula in reverse polish notation. Now go through all elements and modify references one by one as you wish:

/* re-calculate cell references */
for( Ptg ptg  : ptgs )
    if( ptg instanceof RefPtgBase )    //base class for cell reference "things"
    {
        RefPtgBase ref = (RefPtgBase)ptg;
        if( ref.isColRelative() )
            ref.setColumn( ref.getColumn() + 0 );
        if( ref.isRowRelative() )
            ref.setRow( ref.getRow() + 1 );
    }

And you're ready to render "parse things" back to String:

formula = FormulaRenderer.toFormulaString(workbookWrapper, ptgs);
cell.setCellFormula( formula );

Answer 3

I too think that there isn't an easy way to do this.

Even the HSSF and XSSD examples on the POI site e.g. TimesheetDemo do the formula construction manually. e.g. around line 110

String ref = (char)('A' + j) + "3:" + (char)('A' + j) + "12";
cell.setCellFormula("SUM(" + ref + ")");

Answer 4

In my sense, user2622016 is right, except his solution manages only cell references, as opposed to area references (it won't work for =SUM(A1:B8) for instance).

Here's how I fixed this :

private void copyFormula(Sheet sheet, Cell org, Cell dest) {
    if (org == null || dest == null || sheet == null 
            || org.getCellType() != Cell.CELL_TYPE_FORMULA)
        return;
    if (org.isPartOfArrayFormulaGroup())
        return;
    String formula = org.getCellFormula();
    int shiftRows = dest.getRowIndex() - org.getRowIndex();
    int shiftCols = dest.getColumnIndex() - org.getColumnIndex();
    XSSFEvaluationWorkbook workbookWrapper = 
            XSSFEvaluationWorkbook.create((XSSFWorkbook) sheet.getWorkbook());
    Ptg[] ptgs = FormulaParser.parse(formula, workbookWrapper, FormulaType.CELL
            , sheet.getWorkbook().getSheetIndex(sheet));
    for (Ptg ptg : ptgs) {
        if (ptg instanceof RefPtgBase) // base class for cell references
        {
            RefPtgBase ref = (RefPtgBase) ptg;
            if (ref.isColRelative())
                ref.setColumn(ref.getColumn() + shiftCols);
            if (ref.isRowRelative())
                ref.setRow(ref.getRow() + shiftRows);
        } else if (ptg instanceof AreaPtg) // base class for range references
        {
            AreaPtg ref = (AreaPtg) ptg;
            if (ref.isFirstColRelative())
                ref.setFirstColumn(ref.getFirstColumn() + shiftCols);
            if (ref.isLastColRelative())
                ref.setLastColumn(ref.getLastColumn() + shiftCols);
            if (ref.isFirstRowRelative())
                ref.setFirstRow(ref.getFirstRow() + shiftRows);
            if (ref.isLastRowRelative())
                ref.setLastRow(ref.getLastRow() + shiftRows);
        }
    }
    formula = FormulaRenderer.toFormulaString(workbookWrapper, ptgs);
    dest.setCellFormula(formula);
}

I still don't know if I had it correct for all cell formulas, but it works for me, fast and reliable.

Answer 5

I don't think there is. POI would have to parse the formula (taking into account A1 vs. $A$1 vs. $A1 etc.) and I don't believe it has that capacity. When I've done this in the past I've always had to manage this myself. Sorry - not the answer you hoped for!

Answer 6

you can try some third party excel librarys,most of them can handle the relative/absolute range formulas.