1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
|
// Copyright 2019 Nick White.
// Use of this source code is governed by the GPLv3
// license that can be found in the LICENSE file.
// hocr contains structures and functions for parsing and analysing
// hocr files
package hocr
import (
"encoding/xml"
"errors"
"io/ioutil"
"regexp"
"strconv"
"strings"
)
type Hocr struct {
Pages []Page `xml:"body>div"`
}
type Page struct {
Lines []OcrLine `xml:"div>p>span"`
Title string `xml:"title,attr"`
}
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)
}
// Returns the image path for a page from a ocr_page title
func imagePath(s string) (string, error) {
re, err := regexp.Compile(`image ["']([^"']+)["']`)
if err != nil {
return "", err
}
m := re.FindStringSubmatch(s)
return m[1], nil
}
// BoxCoords parses bbox coordinate strings
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
}
// Parse parses a hOCR file
func Parse(b []byte) (Hocr, error) {
var hocr Hocr
err := xml.Unmarshal(b, &hocr)
if err != nil {
return hocr, err
}
return hocr, nil
}
// GetText parses a hOCR file and extracts the text from it
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 _, p := range h.Pages {
for _, l := range p.Lines {
s += LineText(l) + "\n"
}
}
return s, nil
}
// GetAvgConf calculates the average confidence of a hOCR file from
// confidences embedded in each word
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 _, p := range h.Pages {
for _, l := range p.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 _, p := range h.Pages {
for _, l := range p.Lines {
for _, w := range l.Words {
c, err := wordConf(w.Title)
if err != nil {
return confs, err
}
confs = append(confs, c)
}
}
}
return confs, nil
}
|
