Left-pad Freq() output to right-align count values

Author: bitfield

README.md

@@ -474,6 +474,15 @@ sort testdata/freq.input.txt |uniq -c |sort -rn
 script.Stdin().Freq().First(10).Stdout()
 ```
 
+Like `uniq -c`, `Freq()` left-pads its count values if necessary to make them easier to read:
+
+```
+10 apple
+ 4 banana
+ 2 orange
+ 1 kumquat
+```
+
 ### Join
 
 `Join()` reads its input and replaces newlines with spaces, preserving a terminating newline if there is one.

filters.go

@@ -9,6 +9,7 @@ import (
 	"os/exec"
 	"regexp"
 	"sort"
+	"strconv"
 	"strings"
 )
 
@@ -178,18 +179,23 @@ func (p *Pipe) Freq() *Pipe {
 		count int
 	}
 	var freqs = make([]frequency, 0, len(freq))
+	var maxCount int
 	for line, count := range freq {
 		freqs = append(freqs, frequency{line, count})
+		if count > maxCount {
+			maxCount = count
+		}
 	}
 	sort.Slice(freqs, func(i, j int) bool {
 		if freqs[i].count == freqs[j].count {
 			return freqs[i].line < freqs[j].line
 		}
 		return freqs[i].count > freqs[j].count
 	})
+	fieldWidth := len(strconv.Itoa(maxCount))
 	var output strings.Builder
 	for _, item := range freqs {
-		output.WriteString(fmt.Sprintf("%d %s", item.count, item.line))
+		output.WriteString(fmt.Sprintf("%*d %s", fieldWidth, item.count, item.line))
 		output.WriteRune('\n')
 	}
 	return Echo(output.String())

testdata/freq.golden.txt

@@ -1,4 +1,4 @@
-4 apple
-4 banana
-2 orange
-1 kumquat
+10 apple
+ 4 banana
+ 2 orange
+ 1 kumquat

testdata/freq.input.txt

@@ -8,4 +8,10 @@ kumquat
 apple
 apple
 banana
-banana
+banana
+apple
+apple
+apple
+apple
+apple
+apple