# Entry points

`Contour.contour`

— Function```
contour(x, y, z, level::Number)
contour(x, y, z, level::Number, VT::Type)
```

Trace a single contour level, indicated by the argument `level`

. The extracted vertex type maybe be specified by `VT`

.

You'll usually call `lines`

on the output of `contour`

, and then iterate over the result.

`Contour.contours`

— Function`contours`

returns a set of isolines.

You'll usually call `levels`

on the output of `contours`

.

# Accessors

`Contour.level`

— Function`level(c)`

Indicates the `z`

-value at which the contour level `c`

was traced.

`Contour.levels`

— FunctionTurns the output of `contours`

into an iterable with each of the traced contour levels. Each of the objects support `level`

, `coordinates`

, and `vertices`

.

`Contour.lines`

— Function`lines(c)`

Extracts an iterable collection of isolines from a contour level. Use `coordinates`

or `vertices`

to get the coordinates of a line.

`Contour.coordinates`

— Function`coordinates(c)`

Returns the coordinates of the vertices of the contour line as a tuple of lists.

`Contour.vertices`

— Function`vertices(c)`

Returns the vertices of a contour line as a vector of 2-element tuples.

# Utilities

`Contour.contourlevels`

— Function`contourlevels(z,n)`

Examines the values of `z`

and chooses `n`

evenly spaced levels to trace.