tabular

Tabular simplifies printing ASCII tables from command line utilities without the need to pass large sets of data to it's API.

Simply define the table columns and tabular will parse the right format specifier that you can use in your calls to fmt.Printf() or any other function that supports it.

Table columns can be defined once and then reused over and over again making it easy to modify column length and heading in one place. And a subset of columns can be specified during tabular.Print() or tabular.Parse() calls to modify the table's title without redefining it.

Example (also available in example/example.go):

package main

import (
	"fmt"
	"log"

	"github.com/InVisionApp/tabular"
)

var tab tabular.Table

func init() {
	tab = tabular.New()
	tab.Col("env", "Environment", 14)
	tab.Col("cls", "Cluster", 10)
	tab.Col("svc", "Service", 15)
	tab.Col("hst", "Database Host", 20)
	tab.ColRJ("pct", "%CPU", 7)
}

var data = []struct {
	e, c, s, d string
	v          float64
}{
	{
		e: "production",
		c: "cluster-1",
		s: "service-a",
		d: "database-host-1",
		v: 70.01,
	},
	{
		e: "production",
		c: "cluster-1",
		s: "service-b",
		d: "database-host-2",
		v: 99.51,
	},
	{
		e: "production",
		c: "cluster-2",
		s: "service-a",
		d: "database-host-1",
		v: 70.01,
	},
	{
		e: "production",
		c: "cluster-2",
		s: "service-b",
		d: "database-host-2",
		v: 99.51,
	},
}

func main() {
	// Print a subset of columns (Environments and Clusters)
	format := tab.Print("env", "cls")
	for _, x := range data {
		fmt.Printf(format, x.e, x.c)
	}

	// Print All Columns
	format = tab.Print("*")
	for _, x := range data {
		fmt.Printf(format, x.e, x.c, x.s, x.d, x.v)
	}

	// Print All Columns to a custom destination such as a log
	table := tab.Parse("*")
	log.Println(table.Header)
	log.Println(table.SubHeader)
	for _, x := range data {
		log.Printf(table.Format, x.e, x.c, x.s, x.d, x.v)
	}
}

Produces:

Environment    Cluster
-------------- ----------
production     cluster-1
production     cluster-1
production     cluster-2
production     cluster-2

Environment    Cluster    Service         Database Host           %CPU
-------------- ---------- --------------- -------------------- -------
production     cluster-1  service-a       database-host-1        70.01
production     cluster-1  service-b       database-host-2        99.51
production     cluster-2  service-a       database-host-1        70.01
production     cluster-2  service-b       database-host-2        99.51

2018/05/14 11:19:41 Environment    Cluster    Service         Database Host           %CPU
2018/05/14 11:19:41 -------------- ---------- --------------- -------------------- -------
2018/05/14 11:19:41 production     cluster-1  service-a       database-host-1        70.01
2018/05/14 11:19:41 production     cluster-1  service-b       database-host-2        99.51
2018/05/14 11:19:41 production     cluster-2  service-a       database-host-1        70.01
2018/05/14 11:19:41 production     cluster-2  service-b       database-host-2        99.51