From 01d5636bbb33edcace579b0026c89a86536b741d Mon Sep 17 00:00:00 2001
From: Nick White <git@njw.name>
Date: Mon, 10 Feb 2020 16:11:16 +0000
Subject: Add pare-gt tool

---
 pare-gt/main.go | 133 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 133 insertions(+)
 create mode 100644 pare-gt/main.go

diff --git a/pare-gt/main.go b/pare-gt/main.go
new file mode 100644
index 0000000..d07e141
--- /dev/null
+++ b/pare-gt/main.go
@@ -0,0 +1,133 @@
+package main
+
+import (
+	"flag"
+	"fmt"
+	"log"
+	"math/rand"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+)
+
+const usage = `Usage: pare-gt [-n num] gtdir movedir
+
+Moves some of the ground truth from gt-dir into movedir,
+ensuring that the same proportions of each ground truth
+source are represented in the moved section. Proportion of
+ground truth source is calculated by taking the prefix of
+the filename up to the first '-' character.
+`
+
+// Prefixes is a map of the prefix string to a list of filenames
+type Prefixes = map[string][]string
+
+// walker adds any .txt path to prefixes map, under the appropriate
+// prefix (blank if no '-' separator was found)
+func walker(prefixes *Prefixes) filepath.WalkFunc{
+	return func(fpath string, info os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+		if info.IsDir() {
+			return nil
+		}
+		ext := path.Ext(fpath)
+		if ext != ".txt" {
+			return nil
+		}
+		base := path.Base(fpath)
+		idx := strings.Index(base, "-")
+		var prefix string
+		if idx > -1 {
+			prefix = base[0:idx]
+		}
+		noext := strings.TrimSuffix(fpath, ext)
+		(*prefixes)[prefix] = append((*prefixes)[prefix], noext)
+		return nil
+	}
+}
+
+// inStrSlice checks whether a given string is part of a slice of
+// strings
+func inStrSlice(sl []string, s string) bool {
+	for _, v := range sl {
+		if s == v {
+			return true
+		}
+	}
+	return false
+}
+
+func main() {
+	flag.Usage = func() {
+		fmt.Fprintf(flag.CommandLine.Output(), usage)
+		flag.PrintDefaults()
+	}
+	numtopare := flag.Int("n", 10, "Percentage of the ground truth to pare away.")
+	flag.Parse()
+	if flag.NArg() != 2 {
+		flag.Usage()
+		os.Exit(1)
+	}
+
+	for _, d := range flag.Args() {
+		info, err := os.Stat(d)
+		if err != nil || !info.IsDir() {
+			log.Fatalln("Error accessing directory", flag.Arg(0), err)
+		}
+	}
+
+	var prefixes Prefixes
+	prefixes = make(Prefixes)
+	err := filepath.Walk(flag.Arg(0), walker(&prefixes))
+	if err != nil {
+		log.Fatalln("Failed to walk", flag.Arg(0), err)
+	}
+
+	var total, sample int
+	for _, v := range prefixes {
+		total += len(v)
+	//	fmt.Printf("\n%s:\n%s\n", i, v)
+	}
+
+	sample = total / *numtopare
+
+	// filestomove contains the names of files to move minus file extension
+	var filestomove []string
+
+	// select random samples for each prefix, proportional to
+	// the amount of that prefix there are in the whole set
+	for _, prefix := range prefixes {
+		len := len(prefix)
+		if len == 1 {
+			continue
+		}
+		numtoget := int(float64(sample) / float64(total) * float64(len))
+		if numtoget < 1 {
+			numtoget = 1
+		}
+		for i:=0; i<numtoget; i++ {
+			var selected string
+			selected = prefix[rand.Int()%len]
+			// pick a different random selection if the first one is
+			// already in the filestomove slice
+			for inStrSlice(filestomove, selected) {
+				selected = prefix[rand.Int()%len]
+			}
+			filestomove = append(filestomove, selected)
+		}
+	}
+
+	for _, f := range filestomove {
+		fmt.Println("Moving ground truth", f)
+		b := path.Base(f)
+		for _, ext := range []string{".txt", ".png"} {
+			err = os.Rename(f + ext, path.Join(flag.Arg(1), b + ext))
+			if err != nil {
+				log.Fatalln("Error moving file", f + ext, err)
+			}
+		}
+	}
+}
-- 
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