Excel reader does not work for files with just features (no classes) with 3-line header

[markotoplak]

What's wrong and how can we reproduce the problem?

I took the iris data set, removed the class in select rows, and saved it as Excel with "Add type annotations to header".

Loading the file then shows something really strange.

File was written correctly - looks the same as a written file .tab file. I guess the empty line causes issues. A file without this Orange's header works well.

Here is the file: iris.xlsx

[dhiraje1990]

I guess the empty line causes issues.

It is being skipped by the return filter(any, cells) in the get_cells method in ExcelReader before the cells are passed to data_table(). The third header should be flags. Should they be considered plain features if the flags are empty?

[dhiraje1990]

    def get_cells(self) -> Iterable:
        def str_(x):
            return str(x) if x is not None and x not in ExcelReader.ERRORS \
                else ""

        sheet = self._get_active_sheet()
        min_col = sheet.min_column
        max_col = sheet.max_column
        cells = ([str_(cell.value) for cell in row[min_col - 1: max_col]]
                 for row in sheet.iter_rows(sheet.min_row, sheet.max_row + 1))

        header_row_num = 3 if self.OPTIONAL_TYPE_ANNOTATIONS else 1
        header = list(islice(cells, header_row_num))
        data = filter(any, cells)  # only filter empties in data rows
        return chain(header, data)

This works on my local and all test cases passed. but will 3 be enough?