Golang : Format numbers to nearest thousands such as kilos millions billions and trillions
Problem:
You want to format a given number to the nearest thousands such as kilos, millions, billions, and trillions. For example, rounding up a counter number similar to the Facebook or Twitter share button. Or perhaps, your fintech startup is servicing multiple currencies from millions to billions to trillions and you want to truncate the numbers for easier reading and digesting. How to do that?
Solution:
The code that follows should be able to convert both positive and negative numbers to the nearest thousands up to trillions. What it does is to figure out how many parts of the number are in 1000 block and base on the number of 1000 blocks, pick the appropriate measurement, such as k
for kilos, m
for millions and so on. It will leave any number less than 999.5 rounded by mostly unmolested.
Here you go!
package main
import (
"fmt"
"math"
"strconv"
"strings"
)
// credit to https://github.com/DeyV/gotools/blob/master/numbers.go
func RoundPrec(x float64, prec int) float64 {
if math.IsNaN(x) || math.IsInf(x, 0) {
return x
}
sign := 1.0
if x < 0 {
sign = -1
x *= -1
}
var rounder float64
pow := math.Pow(10, float64(prec))
intermed := x * pow
_, frac := math.Modf(intermed)
if frac >= 0.5 {
rounder = math.Ceil(intermed)
} else {
rounder = math.Floor(intermed)
}
return rounder / pow * sign
}
func NumberFormat(number float64, decimals int, decPoint, thousandsSep string) string {
if math.IsNaN(number) || math.IsInf(number, 0) {
number = 0
}
var ret string
var negative bool
if number < 0 {
number *= -1
negative = true
}
d, fract := math.Modf(number)
if decimals <= 0 {
fract = 0
} else {
pow := math.Pow(10, float64(decimals))
fract = RoundPrec(fract*pow, 0)
}
if thousandsSep == "" {
ret = strconv.FormatFloat(d, 'f', 0, 64)
} else if d >= 1 {
var x float64
for d >= 1 {
d, x = math.Modf(d / 1000)
x = x * 1000
ret = strconv.FormatFloat(x, 'f', 0, 64) + ret
if d >= 1 {
ret = thousandsSep + ret
}
}
} else {
ret = "0"
}
fracts := strconv.FormatFloat(fract, 'f', 0, 64)
// "0" pad left
for i := len(fracts); i < decimals; i++ {
fracts = "0" + fracts
}
ret += decPoint + fracts
if negative {
ret = "-" + ret
}
return ret
}
func RoundInt(input float64) int {
var result float64
if input < 0 {
result = math.Ceil(input - 0.5)
} else {
result = math.Floor(input + 0.5)
}
// only interested in integer, ignore fractional
i, _ := math.Modf(result)
return int(i)
}
func FormatNumber(input float64) string {
x := RoundInt(input)
xFormatted := NumberFormat(float64(x), 2, ".", ",")
return xFormatted
}
func NearestThousandFormat(num float64) string {
if math.Abs(num) < 999.5 {
xNum := FormatNumber(num)
xNumStr := xNum[:len(xNum)-3]
return string(xNumStr)
}
xNum := FormatNumber(num)
// first, remove the .00 then convert to slice
xNumStr := xNum[:len(xNum)-3]
xNumCleaned := strings.Replace(xNumStr, ",", " ", -1)
xNumSlice := strings.Fields(xNumCleaned)
count := len(xNumSlice) - 2
unit := [4]string{"k", "m", "b", "t"}
xPart := unit[count]
afterDecimal := ""
if xNumSlice[1][0] != 0 {
afterDecimal = "." + string(xNumSlice[1][0])
}
final := xNumSlice[0] + afterDecimal + xPart
return final
}
func main() {
num := 10
fmt.Println(num, " = ", NearestThousandFormat(float64(num)))
num2 := 100.00
fmt.Println(num2, " = ", NearestThousandFormat(num2))
num3 := 1000
fmt.Println(num3, " = ", NearestThousandFormat(float64(num3)))
num4 := 10000.00
fmt.Println(num4, " = ", NearestThousandFormat(num4))
num5 := 3123456789.12 // billion
fmt.Println(num5, " = ", NearestThousandFormat(num5))
num6 := 999.4
fmt.Println(num6, " = ", NearestThousandFormat(num6))
num7 := -372712
fmt.Println(num7, " = ", NearestThousandFormat(float64(num7)))
num8 := -37271922
fmt.Println(num8, " = ", NearestThousandFormat(float64(num8)))
num9 := -198
fmt.Println(num9, " = ", NearestThousandFormat(float64(num9)))
}
Output:
10 = 10
100 = 100
1000 = 1.0k
10000 = 10.0k
3.12345678912e+09 = 3.1b
999.4 = 999
-372712 = -372.7k
-37271922 = -37.2m
-198 = -198
Happy counting and coding!
References:
https://www.socketloop.com/tutorials/golang-transform-comma-separated-string-to-slice-example
See also : Golang : How to convert a number to words
By Adam Ng
IF you gain some knowledge or the information here solved your programming problem. Please consider donating to the less fortunate or some charities that you like. Apart from donation, planting trees, volunteering or reducing your carbon footprint will be great too.
Advertisement
Tutorials
+10k Golang : Proper way to test CIDR membership of an IP 4 or 6 address example
+5.2k Linux/Unix : Commands that you need to be careful about
+21.3k Golang : Convert Unix timestamp to UTC timestamp
+14.2k Golang : Validate hostname
+7.4k Golang: Prevent over writing file with md5 hash
+12.2k Golang : error parsing regexp: invalid or unsupported Perl syntax
+21.1k Golang : Repeat a character by multiple of x factor
+3.6k Javascript : Detect when console is activated and do something about it
+2.9k Java : Random alphabets, alpha-numeric or numbers only string generator
+9k Golang : Simple Jawi(Yawi) to Rumi(Latin/Romanize) converter
+18k Golang : Check if directory exist and create if does not exist
+6k Golang : Levenshtein distance example