sortstr

Sort slices of strings based on multiple indices or column headers. Reverse sort is possible by providing negative index values or prefixing column header titles with -. Note that indices are not zero based, but start with 1. If an index is out of range, an empty string will be used for comparing, rather than throwing a runtime panic.

Normally you only need to use this function:

By(rows, indices)

or these two together:

NewHeaders(titles)
ByHeaders(headers, rows, titles)

Only if you need to sort the same rows multiple times in different orders, you'll need to use the Multi type directly.

This was developed with the xlsx package in mind, but can be used independently.

Examples

Using indices:

var rows = [][]string{
	{"John Lennon", "1968", "Let It Be"},
	{"John Lennon", "1965", "Let It Be"},
	{"John Lennon", "1965", "12-Bar Original"},
	{"Paul McCartney", "1963", "All My Loving"},
	{"George Harrison", "1968",
		"While My Guitar Gently Weeps"},
	{"Ringo Star", "1965", "Untitled"},
	{"Ringo Star"},
}
sortstr.By(rows, -1, 3, 2) // reverse order for first column
sortstr.Print("By author, title, year", rows, ", ")
sortstr.By(rows, 2, 1, 3)
sortstr.Print("By year, author, title", rows, ", ")
sortstr.By(rows, 3, 1, 2)
sortstr.Print("By title, author, year", rows, ", ")

Output:

By author, title, year:
Ringo Star
Ringo Star, 1965, Untitled
Paul McCartney, 1963, All My Loving
John Lennon, 1965, 12-Bar Original
John Lennon, 1965, Let It Be
John Lennon, 1968, Let It Be
George Harrison, 1968, While My Guitar Gently Weeps

By year, author, title:
Ringo Star
Paul McCartney, 1963, All My Loving
John Lennon, 1965, 12-Bar Original
John Lennon, 1965, Let It Be
Ringo Star, 1965, Untitled
George Harrison, 1968, While My Guitar Gently Weeps
John Lennon, 1968, Let It Be

By title, author, year:
Ringo Star
John Lennon, 1965, 12-Bar Original
Paul McCartney, 1963, All My Loving
John Lennon, 1965, Let It Be
John Lennon, 1968, Let It Be
Ringo Star, 1965, Untitled
George Harrison, 1968, While My Guitar Gently Weeps

Using column headers:

titles := []string{"author", "year", "title"}
headers := sortstr.NewHeaders(titles)
rows := [][]string{
	{"John Lennon", "1968", "Let It Be"},
	{"John Lennon", "1965", "Let It Be"},
	{"John Lennon", "1965", "12-Bar Original"},
	{"Paul McCartney", "1963", "All My Loving"},
	{"George Harrison", "1968",
		"While My Guitar Gently Weeps"},
	{"Ringo Star", "1965", "Untitled"},
}
err := sortstr.ByHeaders(headers, rows,
	"-author", "title", "year") // reverse order for author
if err != nil {
	fmt.Println("Unknown column header")
}
sortstr.Print("By -author, title, year", rows, ", ")
err = sortstr.ByHeaders(headers, rows,
	"year", "author", "title")
if err != nil {
	fmt.Println("Unknown column header")
} else {
	sortstr.Print("By year, author, title", rows, ", ")
}
err = sortstr.ByHeaders(headers, rows,
	"title", "author", "year")
if err != nil {
	fmt.Println("Unknown column header")
} else {
	sortstr.Print("By title, author, year", rows, ", ")
}
err = sortstr.ByHeaders(headers, rows,
	"title", "author", "disc")
if err != nil {
	fmt.Println("Unknown column header")
} else {
	sortstr.Print("By title, author, year", rows, ", ")
}

Output:

By -author, title, year:
Ringo Star, 1965, Untitled
Paul McCartney, 1963, All My Loving
John Lennon, 1965, 12-Bar Original
John Lennon, 1965, Let It Be
John Lennon, 1968, Let It Be
George Harrison, 1968, While My Guitar Gently Weeps

By year, author, title:
Paul McCartney, 1963, All My Loving
John Lennon, 1965, 12-Bar Original
John Lennon, 1965, Let It Be
Ringo Star, 1965, Untitled
George Harrison, 1968, While My Guitar Gently Weeps
John Lennon, 1968, Let It Be

By title, author, year:
John Lennon, 1965, 12-Bar Original
Paul McCartney, 1963, All My Loving
John Lennon, 1965, Let It Be
John Lennon, 1968, Let It Be
Ringo Star, 1965, Untitled
George Harrison, 1968, While My Guitar Gently Weeps
Unknown column header

Documentation

See godoc for more documentation and examples.

License

Released under the MIT License.