Add documentation for grids

Author: simonrw

src/grid.rs

@@ -1,11 +1,51 @@
+#![deny(missing_docs)]
+
+//! Configure a grid on a plot.
+//!
+//! Grids allow for easier estimating of data values. This module allows the configuration of grids
+//! on plots.
+//!
+//! Grids are created by creating a `Grid` definition, and adding it to a plot:
+//!
+//! The grid lines for `plotlib` are rendered
+//! _underneath_ the data so as to not detract from the data.
+//!
+//! # Examples
+//!
+//! ```rust
+//! # use plotlib::view::ContinuousView;
+//! use plotlib::grid::Grid;
+//! # use plotlib::style::Line;
+//! # use plotlib::view::View;
+//!
+//! # let l1 = plotlib::line::Line::new(&[(0., 1.), (2., 1.5), (3., 1.2), (4., 1.1)])
+//! #    .style(plotlib::line::Style::new().colour("burlywood"));
+//! // let l1 = Line::new() ...
+//! let mut v = ContinuousView::new().add(&l1);
+//!
+//! // 3 vertical lines and 8 horizontal lines
+//! v.add_grid(Grid::new(3, 8));
+//!
+//! // Render plot
+//! ```
+
+// Internal type representing the logic of when do we render only horizontal lines, and when do we
+// render a full grid
 pub(crate) enum GridType<'a> {
     HorizontalOnly(&'a Grid),
     Both(&'a Grid),
 }
 
+/// Configuration for the grid on a plot
+///
+/// Supports changing the number of grid lines for the x and y dimensions.
+/// **Note:** for categorical plots, only horizontal lines will be shown.
 pub struct Grid {
+    /// Number of vertical grid lines (defaults to 3)
     pub nx: u32,
+    /// Number of horizontal grid lines (defaults to 3)
     pub ny: u32,
+    /// Color of the grid lines (defaults to "darkgrey")
     pub color: String,
 }
 
@@ -16,6 +56,9 @@ impl Default for Grid {
 }
 
 impl Grid {
+    /// Create a new grid with `nx` vertical and `ny` horizontal grid lines
+    ///
+    /// The default colour is "darkgrey".
     pub fn new(nx: u32, ny: u32) -> Grid {
         Grid {
             nx,