`pllegend`: Plot legend using discretely annotated filled boxes, lines, and/or lines of symbols
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#### `pllegend`: Plot legend using discretely annotated filled boxes, lines, and/or lines of symbols

`pllegend (` | p_legend_width,
| p_legend_height,
| opt,
| position,
| x,
| y,
| plot_width,
| bg_color,
| bb_color,
| bb_style,
| nrow,
| ncolumn,
| nlegend,
| opt_array,
| text_offset,
| text_scale,
| text_spacing,
| test_justification,
| text_colors,
| text,
| box_colors,
| box_patterns,
| box_scales,
| box_line_widths,
| line_colors,
| line_styles,
| line_widths,
| symbol_colors,
| symbol_scales,
| symbol_numbers,
| symbols`)`;

Routine for creating a discrete plot legend with a plotted filled box, line, and/or line of symbols for each annotated legend entry. (See `plcolorbar` for similar functionality for creating continuous color bars.) The arguments of pllegend provide control over the location and size of the legend as well as the location and characteristics of the elements (most of which are optional) within that legend. The resulting legend is clipped at the boundaries of the current subpage. (N.B. the adopted coordinate system used for some of the parameters is defined in the documentation of the ``position`` parameter.)

`p_legend_width` (`PLFLT *`, output)

  Pointer to a location which contains (after the call) the legend width in adopted coordinates. This quantity is calculated from ``plot_width``, ``text_offset``, ``ncolumn`` (possibly modified inside the routine depending on ``nlegend`` and ``nrow``), and the length (calculated internally) of the longest text string.

`p_legend_height` (`PLFLT *`, output)

  Pointer to a location which contains (after the call) the legend height in adopted coordinates. This quantity is calculated from ``text_scale``, ``text_spacing``, and ``nrow`` (possibly modified inside the routine depending on ``nlegend`` and ``nrow``).

`opt` (`PLINT`, input)

  ``opt`` contains bits controlling the overall legend. If the `PL_LEGEND_TEXT_LEFT` bit is set, put the text area on the left of the legend and the plotted area on the right. Otherwise, put the text area on the right of the legend and the plotted area on the left. If the `PL_LEGEND_BACKGROUND` bit is set, plot a (semi-transparent) background for the legend. If the `PL_LEGEND_BOUNDING_BOX` bit is set, plot a bounding box for the legend. If the `PL_LEGEND_ROW_MAJOR` bit is set and (both of the possibly internally transformed) ``nrow`` > 1 and ``ncolumn`` > 1, then plot the resulting array of legend entries in row-major order. Otherwise, plot the legend entries in column-major order.

`position` (`PLINT`, input)

  ``position`` contains bits which control the overall position of the legend and the definition of the adopted coordinates used for positions just like what is done for the position argument for `plcolorbar`. However, note that the defaults for the position bits (see below) are different than the `plcolorbar` case. The combination of the `PL_POSITION_LEFT`, `PL_POSITION_RIGHT`, `PL_POSITION_TOP`, `PL_POSITION_BOTTOM`, `PL_POSITION_INSIDE`, and `PL_POSITION_OUTSIDE` bits specifies one of the 16 possible standard positions (the 4 corners and centers of the 4 sides for both the inside and outside cases) of the legend relative to the adopted coordinate system. The corner positions are specified by the appropriate combination of two of the `PL_POSITION_LEFT`, `PL_POSITION_RIGHT`, `PL_POSITION_TOP`, and `PL_POSITION_BOTTOM` bits while the sides are specified by a single value of one of those bits. The adopted coordinates are normalized viewport coordinates if the `PL_POSITION_VIEWPORT` bit is set or normalized subpage coordinates if the `PL_POSITION_SUBPAGE` bit is set. Default position bits: If none of `PL_POSITION_LEFT`, `PL_POSITION_RIGHT`, `PL_POSITION_TOP`, or `PL_POSITION_BOTTOM` are set, then use the combination of `PL_POSITION_RIGHT` and `PL_POSITION_TOP`. If neither of `PL_POSITION_INSIDE` or `PL_POSITION_OUTSIDE` is set, use `PL_POSITION_INSIDE`. If neither of `PL_POSITION_VIEWPORT` or `PL_POSITION_SUBPAGE` is set, use `PL_POSITION_VIEWPORT`.

`x` (`PLFLT`, input)

  X offset of the legend position in adopted coordinates from the specified standard position of the legend. For positive x, the direction of motion away from the standard position is inward/outward from the standard corner positions or standard left or right positions if the `PL_POSITION_INSIDE`/`PL_POSITION_OUTSIDE` bit is set in ``position``. For the standard top or bottom positions, the direction of motion is toward positive X.

`y` (`PLFLT`, input)

  Y offset of the legend position in adopted coordinates from the specified standard position of the legend. For positive y, the direction of motion away from the standard position is inward/outward from the standard corner positions or standard top or bottom positions if the `PL_POSITION_INSIDE`/`PL_POSITION_OUTSIDE` bit is set in ``position``. For the standard left or right positions, the direction of motion is toward positive Y.

`plot_width` (`PLFLT`, input)

  Horizontal width in adopted coordinates of the plot area (where the colored boxes, lines, and/or lines of symbols are drawn) of the legend.

`bg_color` (`PLINT`, input)

  The cmap0 color of the background for the legend (`PL_LEGEND_BACKGROUND`).

`bb_color` (`PLINT`, input)

  The cmap0 color of the bounding-box line for the legend (`PL_LEGEND_BOUNDING_BOX`).

`bb_style` (`PLINT`, input)

  The pllsty style number for the bounding-box line for the legend (`PL_LEGEND_BACKGROUND`).

`nrow` (`PLINT`, input)

  The cmap0 index of the background color for the legend (`PL_LEGEND_BACKGROUND`).

`ncolumn` (`PLINT`, input)

  The cmap0 index of the background color for the legend (`PL_LEGEND_BACKGROUND`).

`nlegend` (`PLINT`, input)

  Number of legend entries. N.B. The total vertical height of the legend in adopted coordinates is calculated internally from ``nlegend``, ``text_scale`` (see below), and ``text_spacing`` (see below).

`opt_array` (`const PLINT *`, input)

  Array of nlegend values of options to control each individual plotted area corresponding to a legend entry. If the `PL_LEGEND_NONE` bit is set, then nothing is plotted in the plotted area. If the `PL_LEGEND_COLOR_BOX`, `PL_LEGEND_LINE`, and/or `PL_LEGEND_SYMBOL` bits are set, the area corresponding to a legend entry is plotted with a colored box; a line; and/or a line of symbols.

`text_offset` (`PLFLT`, input)

  Offset of the text area from the plot area in units of character width. N.B. The total horizontal width of the legend in adopted coordinates is calculated internally from `plot_width` (see above), `text_offset`, and length (calculated internally) of the longest text string.

`text_scale` (`PLFLT`, input)

  Character height scale for text annotations. N.B. The total vertical height of the legend in adopted coordinates is calculated internally from `nlegend` (see above), `text_scale`, and `text_spacing` (see below).

`text_spacing` (`PLFLT`, input)

  Vertical spacing in units of the character height from one legend entry to the next. N.B. The total vertical height of the legend in adopted coordinates is calculated internally from `nlegend` (see above), `text_scale` (see above), and `text_spacing`.

`text_justification` (`PLFLT`, input)

  Justification parameter used for text justification. The most common values of text_justification are 0., 0.5, or 1. corresponding to a text that is left justified, centred, or right justified within the text area, but other values are allowed as well.

`text_colors` (`const PLINT *`, input)

  Array of nlegend cmap0 text colors.

`text` (`const char * const *`, input)

  Array of nlegend text string annotations.

`box_colors` (`const PLINT *`, input)

  Array of nlegend cmap0 colors for the discrete colored boxes (`PL_LEGEND_COLOR_BOX`).

`box_patterns` (`const PLINT *`, input)

  Array of nlegend patterns (plpsty indices) for the discrete colored boxes (`PL_LEGEND_COLOR_BOX`).

`box_scales` (`const PLFLT *`, input)

  Array of nlegend scales (units of fraction of character height) for the height of the discrete colored boxes (`PL_LEGEND_COLOR_BOX`).

`box_line_widths` (`const PLFLT *`, input)

  Array of nlegend line widths for the patterns specified by box_patterns (`PL_LEGEND_COLOR_BOX`).

`line_colors` (`const PLINT *`, input)

  Array of nlegend cmap0 line colors (`PL_LEGEND_LINE`).

`line_styles` (`const PLINT *`, input)

  Array of nlegend line styles (plsty indices) (`PL_LEGEND_LINE`).

`line_widths` (`const PLFLT *`, input)

  Array of nlegend line widths (`PL_LEGEND_LINE`).

`symbol_colors` (`const PLINT *`, input)

  Array of nlegend cmap0 symbol colors (`PL_LEGEND_SYMBOL`).

`symbol_scales` (`const PLFLT *`, input)

  Array of nlegend scale values for the symbol height (`PL_LEGEND_SYMBOL`).

`symbol_numbers` (`const PLINT *`, input)

  Array of nlegend numbers of symbols to be drawn across the width of the plotted area (`PL_LEGEND_SYMBOL`).

`symbols` (`const char * const *`, input)

  Array of nlegend symbols (plpoin indices) (`PL_LEGEND_SYMBOL`).

Redacted form: `pllegend(p_legend_width, p_legend_height, opt, position, x, y, plot_width, bg_color, bb_color, bb_style, nrow, ncolumn, opt_array, text_offset, text_scale, text_spacing, test_justification, text_colors, text, box_colors, box_patterns, box_scales, box_line_widths, line_colors, line_styles, line_widths, symbol_colors, symbol_scales, symbol_numbers, symbols)`

This function is used in examples 4, 26, and 33.

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