only.go

package simplecsv

// OnlyThisRows removes all rows that are not in the index and sorts the csv by the index order
// All rows must exist or it fails
// If header is true, the header row is always the first row of the result,
// so including 0 in rowsIndex duplicates the header row in the result
func (s SimpleCsv) OnlyThisRows(rowsIndex []int, header bool) (SimpleCsv, bool) {
	lengthS := len(s)
	for _, v := range rowsIndex {
		if v < 0 || v >= lengthS {
			return s.fail()
		}
	}

	newCsv := SimpleCsv{}
	if header {
		headers := s.GetHeaders()
		newCsv = append(newCsv, headers)
	}

	var rowToAdd []string
	for _, g := range rowsIndex {
		rowToAdd, _ = s.GetRow(g)
		newCsv = append(newCsv, rowToAdd)
	}
	return newCsv, true
}

// OnlyThisFields returns a simplecsv with the fields. At least one field name
// is required (empty or nil fields is rejected).
func (s SimpleCsv) OnlyThisFields(fields []string) (SimpleCsv, bool) {
	positions := s.headerIndex()

	newCsv, err := CreateEmptyCsv(fields)
	if err != nil {
		return s.fail()
	}

	for i := 1; i < len(s); i++ {
		row := make([]string, 0, len(fields))
		for _, field := range fields {
			column, fieldExists := positions[field]
			if fieldExists && column < len(s[i]) {
				row = append(row, s[i][column])
			} else {
				row = append(row, "")
			}
		}
		newCsv, _ = newCsv.AddRow(row)
	}

	return newCsv, true
}