column.go

package simplecsv

// AddEmptyColumn adds an empty column at the end of the csv and returns a
// new csv. The original csv is not modified. columnName must not already
// exist as a header.
func (s SimpleCsv) AddEmptyColumn(columnName string) (SimpleCsv, bool) {
	if len(s) == 0 || s.GetHeaderPosition(columnName) != -1 {
		return s.fail()
	}

	newCsv := make(SimpleCsv, len(s))
	for i, row := range s {
		newRow := make([]string, len(row)+1)
		copy(newRow, row)
		if i == 0 {
			newRow[len(row)] = columnName
		}
		newCsv[i] = newRow
	}
	return newCsv, true
}

// RemoveColumn removes the column in position X and returns a new csv.
// The original csv is not modified
func (s SimpleCsv) RemoveColumn(columnPosition int) (SimpleCsv, bool) {
	if len(s) == 0 || columnPosition < 0 || columnPosition >= len(s[0]) {
		return s.fail()
	}

	newCsv := make(SimpleCsv, len(s))
	for i, row := range s {
		if columnPosition < len(row) {
			newRow := make([]string, 0, len(row)-1)
			newRow = append(newRow, row[:columnPosition]...)
			newRow = append(newRow, row[columnPosition+1:]...)
			newCsv[i] = newRow
		} else {
			newCsv[i] = copyRow(row)
		}
	}
	return newCsv, true
}

// RemoveColumnByName removes column by name
func (s SimpleCsv) RemoveColumnByName(columnName string) (SimpleCsv, bool) {
	var removed bool
	columnPosition := s.GetHeaderPosition(columnName)
	s, removed = s.RemoveColumn(columnPosition)
	return s, removed
}

// GetColumn returns a copy of the data cells of the column in position
// column, skipping the header cell in row 0. The caller can mutate the
// returned slice without affecting the csv. If the csv is empty or the
// column position is not valid, it returns an empty slice and false.
func (s SimpleCsv) GetColumn(column int) ([]string, bool) {
	if len(s) == 0 || column < 0 || column >= len(s[0]) {
		return []string{}, false
	}
	cells := make([]string, 0, len(s)-1)
	for i := 1; i < len(s); i++ {
		cells = append(cells, s[i][column])
	}
	return cells, true
}

// GetColumnByField returns a copy of the data cells of the column with the
// header name columnName, skipping the header cell in row 0. The caller can
// mutate the returned slice without affecting the csv. If the csv is empty
// or the field name does not exist, it returns an empty slice and false.
func (s SimpleCsv) GetColumnByField(columnName string) ([]string, bool) {
	columnPosition := s.GetHeaderPosition(columnName)
	if columnPosition == -1 || len(s) == 0 {
		return []string{}, false
	}
	return s.GetColumn(columnPosition)
}

// SetColumn replaces the data cells of the column in position column with
// the values slice and returns a new csv. The header cell in row 0 is not
// modified and the original csv is not modified. len(values) must equal the
// number of data rows (len(s)-1), because every data row must keep exactly
// one cell in the column. The values are copied, changes to the original
// slice don't affect the csv. If the csv is empty, the column position is
// not valid or the length of values does not match, it returns a copy of
// the csv and false.
func (s SimpleCsv) SetColumn(column int, values []string) (SimpleCsv, bool) {
	if len(s) == 0 || column < 0 || column >= len(s[0]) || len(values) != len(s)-1 {
		return s.fail()
	}
	newCsv := copyRows(s)
	for i, v := range values {
		newCsv[i+1][column] = v
	}
	return newCsv, true
}

// SetColumnByField is SetColumn for the column with the header name
// columnName. If the csv is empty or the field name does not exist, it
// returns a copy of the csv and false.
func (s SimpleCsv) SetColumnByField(columnName string, values []string) (SimpleCsv, bool) {
	columnPosition := s.GetHeaderPosition(columnName)
	if columnPosition == -1 || len(s) == 0 {
		return s.fail()
	}
	return s.SetColumn(columnPosition, values)
}

// MapColumnByField returns a new csv where every data cell of the column
// with the header name columnName is replaced by fn(value, row), called
// once per data row in csv order. row is the csv row index (1 for the
// first data row). The header cell in row 0 is not mapped and the original
// csv is not modified. If the csv is empty or the field name does not
// exist, it returns a copy of the csv and false.
func (s SimpleCsv) MapColumnByField(columnName string, fn func(value string, row int) string) (SimpleCsv, bool) {
	columnPosition := s.GetHeaderPosition(columnName)
	if columnPosition == -1 || len(s) == 0 {
		return s.fail()
	}
	newCsv := copyRows(s)
	for i := 1; i < len(s); i++ {
		newCsv[i][columnPosition] = fn(newCsv[i][columnPosition], i)
	}
	return newCsv, true
}

// FillColumnByField returns a new csv where every data cell of the column
// with the header name columnName is set to value. The header cell in row 0
// is not modified and the original csv is not modified. If the csv is empty
// or the field name does not exist, it returns a copy of the csv and false.
func (s SimpleCsv) FillColumnByField(columnName string, value string) (SimpleCsv, bool) {
	columnPosition := s.GetHeaderPosition(columnName)
	if columnPosition == -1 || len(s) == 0 {
		return s.fail()
	}
	newCsv := copyRows(s)
	for i := 1; i < len(s); i++ {
		newCsv[i][columnPosition] = value
	}
	return newCsv, true
}