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// Copyright 2019 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.
package hocr
import (
"encoding/xml"
"errors"
"io/ioutil"
"regexp"
"strconv"
"strings"
)
type Hocr struct {
Lines []OcrLine `xml:"body>div>div>p>span"`
}
type OcrLine struct {
Class string `xml:"class,attr"`
Id string `xml:"id,attr"`
Title string `xml:"title,attr"`
Words []OcrWord `xml:"span"`
Text string `xml:",chardata"`
}
type OcrWord struct {
Class string `xml:"class,attr"`
Id string `xml:"id,attr"`
Title string `xml:"title,attr"`
Chars []OcrChar `xml:"span"`
Text string `xml:",chardata"`
}
type OcrChar struct {
Class string `xml:"class,attr"`
Id string `xml:"id,attr"`
Title string `xml:"title,attr"`
Chars []OcrChar `xml:"span"`
Text string `xml:",chardata"`
}
// Returns the confidence for a word based on its x_wconf value
func wordConf(s string) (float64, error) {
re, err := regexp.Compile(`x_wconf ([0-9.]+)`)
if err != nil {
return 0.0, err
}
conf := re.FindStringSubmatch(s)
return strconv.ParseFloat(conf[1], 64)
}
func BoxCoords(s string) ([4]int, error) {
var coords [4]int
re, err := regexp.Compile(`bbox ([0-9]+) ([0-9]+) ([0-9]+) ([0-9]+)`)
if err != nil {
return coords, err
}
coordstr := re.FindStringSubmatch(s)
for i := range coords {
c, err := strconv.Atoi(coordstr[i+1])
if err != nil {
return coords, err
}
coords[i] = c
}
return coords, nil
}
func noText(s string) bool {
t := strings.Trim(s, " \n")
return len(t) == 0
}
func Parse(b []byte) (Hocr, error) {
var hocr Hocr
err := xml.Unmarshal(b, &hocr)
if err != nil {
return hocr, err
}
return hocr, nil
}
func GetText(hocrfn string) (string, error) {
var s string
file, err := ioutil.ReadFile(hocrfn)
if err != nil {
return s, err
}
h, err := Parse(file)
if err != nil {
return s, err
}
for _, l := range h.Lines {
s += LineText(l) + "\n"
}
return s, nil
}
func GetAvgConf(hocrfn string) (float64, error) {
file, err := ioutil.ReadFile(hocrfn)
if err != nil {
return 0, err
}
h, err := Parse(file)
if err != nil {
return 0, err
}
var total, num float64
for _, l := range h.Lines {
for _, w := range l.Words {
c, err := wordConf(w.Title)
if err != nil {
return 0, err
}
total += c
num++
}
}
if num == 0 {
return 0, errors.New("No words found")
}
return total / num, nil
}
// GetWordConfs is a utility function that parses a hocr
// file and returns an array containing the confidences
// of each word therein.
func GetWordConfs(hocrfn string) ([]float64, error) {
var confs []float64
file, err := ioutil.ReadFile(hocrfn)
if err != nil {
return confs, err
}
h, err := Parse(file)
if err != nil {
return confs, err
}
for _, l := range h.Lines {
for _, w := range l.Words {
c, err := wordConf(w.Title)
if err != nil {
return confs, err
}
confs = append(confs, c)
}
}
return confs, nil
}
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