[PATCH] boxplot: introduce a default factor

[Jouke W. <j.w...@gm...>]

When a row in the datafile contains no factor, its y-value is stored in
place of the factor identifier, leading to ambiguities.
If the datafile contains
0	0	0	foo
0	1
The second row will be marked as part of the 'foo' boxplot.

This patch fixes that issue.
---
diff -Naur gnuplot-5.0.0.orig/src/gadgets.h gnuplot-5.0.0/src/gadgets.h
--- gnuplot-5.0.0.orig/src/gadgets.h	2015-01-02 22:06:25.488402227 +0100
+++ gnuplot-5.0.0/src/gadgets.h	2015-01-02 22:06:25.458403577 +0100
@@ -279,6 +279,8 @@
 	BOXPLOT_FACTOR_LABELS_X2
 } t_boxplot_factor_labels;
 
+#define DEFAULT_BOXPLOT_FACTOR -1
+
 typedef struct boxplot_style {
     int limit_type;	/* 0 = multiple of interquartile 1 = fraction of points */
     double limit_value;
diff -Naur gnuplot-5.0.0.orig/src/plot2d.c gnuplot-5.0.0/src/plot2d.c
--- gnuplot-5.0.0.orig/src/plot2d.c	2015-01-02 22:06:25.488402227 +0100
+++ gnuplot-5.0.0/src/plot2d.c	2015-01-02 22:08:57.411693594 +0100
@@ -910,19 +910,22 @@
 		store2d_point(current_plot, i++, v[0], v[1], v[0], v[0],
 			      v[1] - v[2], v[1] + v[2], -1.0);
 	    } else {
-		double w;
+		double ylow, w;
 		if (current_plot->plot_style == CANDLESTICKS
 		    || current_plot->plot_style == FINANCEBARS) {
 		    int_warn(storetoken, "This plot style does not work with 1 or 2 cols. Setting to points");
 		    current_plot->plot_style = POINTSTYLE;
-		}
+		} else if (current_plot->plot_style == BOXPLOT)
+		    ylow = DEFAULT_BOXPLOT_FACTOR;
+		else
+		    ylow = v[1];
 		if (current_plot->plot_smooth == SMOOTH_ACSPLINES)
 		    w = 1.0;	/* Unit weights */
 		else
 		    w = -1.0;	/* Auto-width boxes in some styles */
 		/* Set x/y high/low to exactly [x,y] */
 		store2d_point(current_plot, i++, v[0], v[1], 
-						 v[0], v[0], v[1], v[1], w);
+						 v[0], v[0], ylow, v[1], w);
 	    }
 	    break;
 
@@ -1004,7 +1007,7 @@
 
 		case BOXPLOT:	/* x, y, width */
 		    store2d_point(current_plot, i++, v[0], v[1], v[0]-v[2]/2., v[0]+v[2]/2.,
-		    		  v[1], v[1], v[2]);
+				  DEFAULT_BOXPLOT_FACTOR, v[1], v[2]);
 		    break;
 
 #ifdef EAM_OBJECTS
@@ -1513,7 +1516,7 @@
     /* This can happen if the user specifies a non-existent column:
      * fall back to single-boxplot mode */
     if (!string)
-	return 0;
+	return DEFAULT_BOXPLOT_FACTOR;
 
     /* Remove the trailing garbage, quotes etc. from the string */ 
     trimmed_string = df_parse_string_field(string);