From 3307ab89fc2a8297783d2d9d6dc71c69a727644e Mon Sep 17 00:00:00 2001
From: Tom Greig <tag2y19@soton.ac.uk>
Date: Tue, 2 Jul 2024 12:20:39 +0100
Subject: [PATCH] Add log scale options
--xlog, --ylog and --yrlog. pretty() needed tweaking to handle it and
some of the position calculations have been moved around a bit to make
things neater.
---
src/main.c | 226 +++++++++++++++++++++++++++++++++++++++++------------
1 file changed, 176 insertions(+), 50 deletions(-)
diff --git a/src/main.c b/src/main.c
index cf4b87a..eab74d8 100644
--- a/src/main.c
+++ b/src/main.c
@@ -93,6 +93,10 @@ struct context {
} max, min;
} yrange, yrrange;
+ bool xlog;
+ bool ylog;
+ bool yrlog;
+
PangoFontDescription* tick_font_description;
double margins[4];
@@ -167,7 +171,7 @@ static void parse_headers( struct context* context );
static void parse_data( struct context* context );
static void plot_draw( GtkDrawingArea* plot,
cairo_t* cr, int width, int height, void* data );
-static int pretty( double* lo, double* up, int ndiv );
+static int pretty( double* lo, double* up, int ndiv, bool log );
/* PUBLIC FUNK!!! */
@@ -236,6 +240,27 @@ int main( int argc, char** argv ) {
.arg_data = &( context->yrrange.arg ),
.description = "Right y-axis range [min]:[max]",
.arg_description = "range",
+ }, {
+ .long_name = "xlog",
+ .short_name = '\0',
+ .flags = G_OPTION_FLAG_IN_MAIN,
+ .arg = G_OPTION_ARG_NONE,
+ .arg_data = &( context->xlog ),
+ .description = "Use log scale for the x axis",
+ }, {
+ .long_name = "ylog",
+ .short_name = '\0',
+ .flags = G_OPTION_FLAG_IN_MAIN,
+ .arg = G_OPTION_ARG_NONE,
+ .arg_data = &( context->ylog ),
+ .description = "Use log scale for the y axis",
+ }, {
+ .long_name = "yrlog",
+ .short_name = '\0',
+ .flags = G_OPTION_FLAG_IN_MAIN,
+ .arg = G_OPTION_ARG_NONE,
+ .arg_data = &( context->yrlog ),
+ .description = "Use log scale for the right y axis",
}, {
.long_name = "font",
.short_name = 'f',
@@ -1645,11 +1670,14 @@ static void plot_draw( GtkDrawingArea* plot,
yrrange[1] = context->yrrange.max.value;
}
- int xdivs = pretty( &( xrange[0] ), &( xrange[1] ), 10 );
+ int xdivs = pretty(
+ &( xrange[0] ), &( xrange[1] ), 10, context->xlog );
int yldivs = lset ?
- pretty( &( ylrange[0] ), &( ylrange[1] ), 10 ) : 0;
+ pretty(
+ &( ylrange[0] ), &( ylrange[1] ), 10, context->ylog ) : 0;
int yrdivs = rset ?
- pretty( &( yrrange[0] ), &( yrrange[1] ), 10 ) : 0;
+ pretty(
+ &( yrrange[0] ), &( yrrange[1] ), 10, context->yrlog ) : 0;
char tick_buffer[512];
@@ -1672,15 +1700,21 @@ static void plot_draw( GtkDrawingArea* plot,
context->xtick_layouts.layouts[i],
context->tick_font_description );
}
- if ( context->time ) {
- time_t t = xrange[0] + ( (double) i ) / ( xdivs - 1 ) *
+ double x;
+ if ( context->xlog ) {
+ x = pow( 10.0, log10( xrange[0] ) +
+ ( (double) i ) / ( xdivs - 1 ) *
+ log10( xrange[1] / xrange[0] ) );
+ } else {
+ x = xrange[0] + ( (double) i ) / ( xdivs - 1 ) *
( xrange[1] - xrange[0] );
+ }
+ if ( context->time ) {
+ time_t t = (time_t) x;
struct tm* tm = localtime( &t );
strftime( tick_buffer, 512, "%H:%M:%S", tm );
} else {
- sprintf( tick_buffer, "%.3g",
- xrange[0] + ( (double) i ) / ( xdivs - 1 ) *
- ( xrange[1] - xrange[0] ) );
+ sprintf( tick_buffer, "%.3g", x );
}
pango_layout_set_text(
context->xtick_layouts.layouts[i], tick_buffer, -1 );
@@ -1712,8 +1746,16 @@ static void plot_draw( GtkDrawingArea* plot,
context->yltick_layouts.layouts[i],
context->tick_font_description );
}
- sprintf( tick_buffer, "%.3g", ylrange[0] +
- ( (double) i ) / ( yldivs - 1 ) * ( ylrange[1] - ylrange[0] ) );
+ double y;
+ if ( context->ylog ) {
+ y = pow( 10.0, log10( ylrange[0] ) +
+ ( (double) i ) / ( yldivs - 1 ) *
+ log10( ylrange[1] / ylrange[0] ) );
+ } else {
+ y = ylrange[0] + ( (double) i ) / ( yldivs - 1 ) *
+ ( ylrange[1] - ylrange[0] );
+ }
+ sprintf( tick_buffer, "%.3g", y );
pango_layout_set_text(
context->yltick_layouts.layouts[i], tick_buffer, -1 );
int tick_size;
@@ -1744,8 +1786,16 @@ static void plot_draw( GtkDrawingArea* plot,
context->yrtick_layouts.layouts[i],
context->tick_font_description );
}
- sprintf( tick_buffer, "%.3g", yrrange[0] +
- ( (double) i ) / ( yrdivs - 1 ) * ( yrrange[1] - yrrange[0] ) );
+ double y;
+ if ( context->yrlog ) {
+ y = pow( 10.0, log10( yrrange[0] ) +
+ ( (double) i ) / ( yrdivs - 1 ) *
+ log10( yrrange[1] / yrrange[0] ) );
+ } else {
+ y = yrrange[0] + ( (double) i ) / ( yrdivs - 1 ) *
+ ( yrrange[1] - yrrange[0] );
+ }
+ sprintf( tick_buffer, "%.3g", y );
pango_layout_set_text(
context->yrtick_layouts.layouts[i], tick_buffer, -1 );
int tick_size;
@@ -1793,10 +1843,21 @@ static void plot_draw( GtkDrawingArea* plot,
double* yrange = context->data->y[i].axis == LEFT ?
ylrange : yrrange;
- cairo_rectangle( cr, width / 2 - 1,
- height - 5 - ( height - 10 ) *
+ double y;
+ if ( ( context->data->y[i].axis == LEFT &&
+ context->ylog ) ||
+ ( context->data->y[i].axis == RIGHT &&
+ context->yrlog ) ) {
+ y = height - 5 - ( height - 10 ) *
+ log10( context->data->y[i].v / yrange[0] ) /
+ log10( yrange[1] / yrange[0] );
+ } else {
+ y = height - 5 - ( height - 10 ) *
( context->data->y[i].v - yrange[0] ) /
- ( yrange[1] - yrange[0] ) - 1, 2, 2 );
+ ( yrange[1] - yrange[0] );
+ }
+
+ cairo_rectangle( cr, width / 2 - 1, y - 1, 2, 2 );
cairo_fill( cr );
}
@@ -1832,16 +1893,39 @@ static void plot_draw( GtkDrawingArea* plot,
double* yrange = context->data->y[i].axis == LEFT ?
ylrange : yrrange;
+ bool log = ( context->data->y[i].axis == LEFT &&
+ context->ylog ) ||
+ ( context->data->y[i].axis == RIGHT &&
+ context->yrlog );
+
+ double x;
+ double xnext;
+ double y;
+ double ynext;
if ( context->data->y[i].present ) {
- cairo_move_to( cr,
- m[1] + ( width - m[1] - m[3] ) *
+ if ( context->xlog ) {
+ x = m[1] + ( width - m[1] - m[3] ) *
+ log10( context->data->x / xrange[0] ) /
+ log10( xrange[1] / xrange[0] );
+ } else {
+ x = m[1] + ( width - m[1] - m[3] ) *
( context->data->x - xrange[0] ) /
- ( xrange[1] - xrange[0] ),
- height - m[0] - ( height - m[0] - m[2] ) *
+ ( xrange[1] - xrange[0] );
+ }
+
+ if ( log ) {
+ y = height - m[0] - ( height - m[0] - m[2] ) *
+ log10( context->data->y[i].v / yrange[0] ) /
+ log10( yrange[1] / yrange[0] );
+ } else {
+ y = height - m[0] - ( height - m[0] - m[2] ) *
( context->data->y[i].v - yrange[0] ) /
- ( yrange[1] - yrange[0] ) );
+ ( yrange[1] - yrange[0] );
+ }
+
+ cairo_move_to( cr, x, y );
}
@@ -1849,28 +1933,70 @@ static void plot_draw( GtkDrawingArea* plot,
NULL != data;
data = data->next ) {
+ if ( context->xlog ) {
+ x = m[1] + ( width - m[1] - m[3] ) *
+ log10( data->x / xrange[0] ) /
+ log10( xrange[1] / xrange[0] );
+ } else {
+ x = m[1] + ( width - m[1] - m[3] ) *
+ ( data->x - xrange[0] ) /
+ ( xrange[1] - xrange[0] );
+ }
+
if ( data->y[i].present ) {
- if ( NULL != data->next && data->next->y[i].present ) {
+ if ( log ) {
+ y = height - m[0] - ( height - m[0] - m[2] ) *
+ log10( data->y[i].v / yrange[0] ) /
+ log10( yrange[1] / yrange[0] );
+ } else {
+ y = height - m[0] - ( height - m[0] - m[2] ) *
+ ( data->y[i].v - yrange[0] ) /
+ ( yrange[1] - yrange[0] );
+ }
+
+ }
+
+ if ( NULL != data->next ) {
+
+ if ( context->xlog ) {
+ xnext = m[1] + ( width - m[1] - m[3] ) *
+ log10( data->next->x / xrange[0] ) /
+ log10( xrange[1] / xrange[0] );
+ } else {
+ xnext = m[1] + ( width - m[1] - m[3] ) *
+ ( data->next->x - xrange[0] ) /
+ ( xrange[1] - xrange[0] );
+ }
- cairo_line_to( cr,
- m[1] + ( width - m[1] - m[3] ) *
- ( data->next->x - xrange[0] ) /
- ( xrange[1] - xrange[0] ),
- height - m[0] - ( height - m[0] - m[2] ) *
+ if ( data->next->y[i].present ) {
+
+ if ( log ) {
+ ynext = height - m[0] -
+ ( height - m[0] - m[2] ) *
+ log10( data->next->y[i].v / yrange[0] ) /
+ log10( yrange[1] / yrange[0] );
+ } else {
+ ynext = height - m[0] -
+ ( height - m[0] - m[2] ) *
( data->next->y[i].v - yrange[0] ) /
- ( yrange[1] - yrange[0] ) );
+ ( yrange[1] - yrange[0] );
+ }
+
+ }
+
+ }
+
+ if ( data->y[i].present ) {
+
+ if ( NULL != data->next && data->next->y[i].present ) {
+
+ cairo_line_to( cr, xnext, ynext );
} else if ( NULL == data->prev ||
!data->prev->y[i].present ) {
- cairo_rectangle( cr,
- m[1] + ( width - m[1] - m[3] ) *
- ( data->x - xrange[0] ) /
- ( xrange[1] - xrange[0] ),
- height - m[0] - ( height - m[0] - m[2] ) *
- ( data->y[i].v - yrange[0] ) /
- ( yrange[1] - yrange[0] ) - 1, 2, 2 );
+ cairo_rectangle( cr, x - 1, y - 1, 2, 2 );
cairo_fill( cr );
} else {
@@ -1883,13 +2009,7 @@ static void plot_draw( GtkDrawingArea* plot,
if ( NULL != data->next && data->next->y[i].present ) {
- cairo_move_to( cr,
- m[1] + ( width - m[1] - m[3] ) *
- ( data->next->x - xrange[0] ) /
- ( xrange[1] - xrange[0] ),
- height - m[0] - ( height - m[0] - m[2] ) *
- ( data->next->y[i].v - yrange[0] ) /
- ( yrange[1] - yrange[0] ) );
+ cairo_move_to( cr, xnext, ynext );
}
@@ -2134,10 +2254,10 @@ static void plot_draw( GtkDrawingArea* plot,
}
-static int pretty( double* lo, double* up, int ndiv ) {
+static int pretty( double* lo, double* up, int ndiv, bool log ) {
/* Shamelessly filched from the R language's source code.
- * (src/appl/pretty.c) */
+ * (src/appl/pretty.c), adapted for log scales */
#define rounding_eps 1E-10
#define h 1.5
@@ -2148,6 +2268,10 @@ static int pretty( double* lo, double* up, int ndiv ) {
double lo_ = *lo;
double up_ = *up;
+ if ( log ) {
+ lo_ = log10( lo_ );
+ up_ = log10( up_ );
+ }
double dx = up_ - lo_;
double cell = fabs( lo_ ) > fabs( up_ ) ? fabs( lo_ ) : fabs( up_ );
@@ -2197,11 +2321,11 @@ static int pretty( double* lo, double* up, int ndiv ) {
double ns = floor( lo_ / unit + rounding_eps );
double nu = ceil( up_ / unit - rounding_eps );
- while ( ns * unit > *lo + rounding_eps * unit ) {
+ while ( ns * unit > lo_ + rounding_eps * unit ) {
ns--;
}
- while ( nu * unit < *up - rounding_eps * unit ) {
+ while ( nu * unit < up_ - rounding_eps * unit ) {
nu++;
}
@@ -2225,11 +2349,13 @@ static int pretty( double* lo, double* up, int ndiv ) {
ndiv = k;
}
- if ( ns * unit < *lo ) {
- *lo = ns * unit;
+ *lo = ns * unit;
+ if ( log ) {
+ *lo = pow( 10.0, *lo );
}
- if ( nu * unit > *up ) {
- *up = nu * unit;
+ *up = nu * unit;
+ if ( log ) {
+ *up = pow( 10.0, *up );
}
return ndiv + 1;
--
GitLab