tesseract 4.1.1
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LLSQ Class Reference

#include <linlsq.h>

Public Member Functions

 LLSQ ()
 
void clear ()
 
void add (double x, double y)
 
void add (double x, double y, double weight)
 
void add (const LLSQ &other)
 
void remove (double x, double y)
 
int32_t count () const
 
double m () const
 
double c (double m) const
 
double rms (double m, double c) const
 
double pearson () const
 
FCOORD mean_point () const
 
double rms_orth (const FCOORD &dir) const
 
FCOORD vector_fit () const
 
double covariance () const
 
double x_variance () const
 
double y_variance () const
 

Detailed Description

Definition at line 28 of file linlsq.h.

Constructor & Destructor Documentation

◆ LLSQ()

LLSQ::LLSQ ( )
inline

Definition at line 30 of file linlsq.h.

30 { // constructor
31 clear(); // set to zeros
32 }
void clear()
Definition: linlsq.cpp:32

Member Function Documentation

◆ add() [1/3]

void LLSQ::add ( const LLSQ other)

Definition at line 66 of file linlsq.cpp.

66 {
67 total_weight += other.total_weight;
68 sigx += other.sigx; // update accumulators
69 sigy += other.sigy;
70 sigxx += other.sigxx;
71 sigxy += other.sigxy;
72 sigyy += other.sigyy;
73}

◆ add() [2/3]

void LLSQ::add ( double  x,
double  y 
)

Definition at line 48 of file linlsq.cpp.

48 { // add an element
49 total_weight++; // count elements
50 sigx += x; // update accumulators
51 sigy += y;
52 sigxx += x * x;
53 sigxy += x * y;
54 sigyy += y * y;
55}

◆ add() [3/3]

void LLSQ::add ( double  x,
double  y,
double  weight 
)

Definition at line 57 of file linlsq.cpp.

57 {
58 total_weight += weight;
59 sigx += x * weight; // update accumulators
60 sigy += y * weight;
61 sigxx += x * x * weight;
62 sigxy += x * y * weight;
63 sigyy += y * y * weight;
64}

◆ c()

double LLSQ::c ( double  m) const

Definition at line 116 of file linlsq.cpp.

116 { // get constant
117 if (total_weight > 0.0)
118 return (sigy - m * sigx) / total_weight;
119 else
120 return 0; // too little
121}
double m() const
Definition: linlsq.cpp:100

◆ clear()

void LLSQ::clear ( )

Definition at line 32 of file linlsq.cpp.

32 { // initialize
33 total_weight = 0.0; // no elements
34 sigx = 0.0; // update accumulators
35 sigy = 0.0;
36 sigxx = 0.0;
37 sigxy = 0.0;
38 sigyy = 0.0;
39}

◆ count()

int32_t LLSQ::count ( ) const
inline

Definition at line 43 of file linlsq.h.

43 { // no of elements
44 return static_cast<int>(total_weight + 0.5);
45 }

◆ covariance()

double LLSQ::covariance ( ) const
inline

Definition at line 75 of file linlsq.h.

75 {
76 if (total_weight > 0.0)
77 return (sigxy - sigx * sigy / total_weight) / total_weight;
78 else
79 return 0.0;
80 }

◆ m()

double LLSQ::m ( ) const

Definition at line 100 of file linlsq.cpp.

100 { // get gradient
101 double covar = covariance();
102 double x_var = x_variance();
103 if (x_var != 0.0)
104 return covar / x_var;
105 else
106 return 0.0; // too little
107}
double x_variance() const
Definition: linlsq.h:81
double covariance() const
Definition: linlsq.h:75

◆ mean_point()

FCOORD LLSQ::mean_point ( ) const

Definition at line 166 of file linlsq.cpp.

166 {
167 if (total_weight > 0.0) {
168 return FCOORD(sigx / total_weight, sigy / total_weight);
169 } else {
170 return FCOORD(0.0f, 0.0f);
171 }
172}
Definition: points.h:189

◆ pearson()

double LLSQ::pearson ( ) const

Definition at line 153 of file linlsq.cpp.

153 { // get correlation
154 double r = 0.0; // Correlation is 0 if insufficient data.
155
156 double covar = covariance();
157 if (covar != 0.0) {
158 double var_product = x_variance() * y_variance();
159 if (var_product > 0.0)
160 r = covar / std::sqrt(var_product);
161 }
162 return r;
163}
double y_variance() const
Definition: linlsq.h:87

◆ remove()

void LLSQ::remove ( double  x,
double  y 
)

Definition at line 82 of file linlsq.cpp.

82 { // delete an element
83 if (total_weight <= 0.0) // illegal
84 EMPTY_LLSQ.error("LLSQ::remove", ABORT, nullptr);
85 total_weight--; // count elements
86 sigx -= x; // update accumulators
87 sigy -= y;
88 sigxx -= x * x;
89 sigxy -= x * y;
90 sigyy -= y * y;
91}
constexpr ERRCODE EMPTY_LLSQ("Can't delete from an empty LLSQ")
@ ABORT
Definition: errcode.h:29
void error(const char *caller, TessErrorLogCode action, const char *format,...) const
Definition: errcode.cpp:35

◆ rms()

double LLSQ::rms ( double  m,
double  c 
) const

Definition at line 130 of file linlsq.cpp.

130 { // get error
131 double error; // total error
132
133 if (total_weight > 0) {
134 error = sigyy + m * (m * sigxx + 2 * (c * sigx - sigxy)) + c *
135 (total_weight * c - 2 * sigy);
136 if (error >= 0)
137 error = std::sqrt(error / total_weight); // sqrt of mean
138 else
139 error = 0;
140 } else {
141 error = 0; // too little
142 }
143 return error;
144}
double c(double m) const
Definition: linlsq.cpp:116

◆ rms_orth()

double LLSQ::rms_orth ( const FCOORD dir) const

Definition at line 195 of file linlsq.cpp.

195 {
196 FCOORD v = !dir;
197 v.normalise();
198 return std::sqrt(x_variance() * v.x() * v.x() +
199 2 * covariance() * v.x() * v.y() +
200 y_variance() * v.y() * v.y());
201}
float y() const
Definition: points.h:210
bool normalise()
Convert to unit vec.
Definition: points.cpp:29
float x() const
Definition: points.h:207

◆ vector_fit()

FCOORD LLSQ::vector_fit ( ) const

Definition at line 251 of file linlsq.cpp.

251 {
252 double x_var = x_variance();
253 double y_var = y_variance();
254 double covar = covariance();
255 double theta = 0.5 * atan2(2.0 * covar, x_var - y_var);
256 FCOORD result(cos(theta), sin(theta));
257 return result;
258}

◆ x_variance()

double LLSQ::x_variance ( ) const
inline

Definition at line 81 of file linlsq.h.

81 {
82 if (total_weight > 0.0)
83 return (sigxx - sigx * sigx / total_weight) / total_weight;
84 else
85 return 0.0;
86 }

◆ y_variance()

double LLSQ::y_variance ( ) const
inline

Definition at line 87 of file linlsq.h.

87 {
88 if (total_weight > 0.0)
89 return (sigyy - sigy * sigy / total_weight) / total_weight;
90 else
91 return 0.0;
92 }

The documentation for this class was generated from the following files: