contour_generator

contourpy.contour_generator(x=None, y=None, z=None, *, name='serial', corner_mask=None, line_type=None, fill_type=None, chunk_size=None, chunk_count=None, total_chunk_count=None, quad_as_tri=False, z_interp=<ZInterp.Linear: 1>, thread_count=0)[source]

Create and return a ContourGenerator object.

The class and properties of the returned ContourGenerator are determined by the function arguments, with sensible defaults.

Parameters:

  • x (array-like of shape (ny, nx) or (nx,), optional) – The x-coordinates of the z values. May be 2D with the same shape as z.shape, or 1D with length nx = z.shape[1]. If not specified are assumed to be np.arange(nx). Must be ordered monotonically.

  • y (array-like of shape (ny, nx) or (ny,), optional) – The y-coordinates of the z values. May be 2D with the same shape as z.shape, or 1D with length ny = z.shape[0]. If not specified are assumed to be np.arange(ny). Must be ordered monotonically.

  • z (array-like of shape (ny, nx), may be a masked array) – The 2D gridded values to calculate the contours of. May be a masked array, and any invalid values (np.inf or np.nan) will also be masked out.

  • name (str) – Algorithm name, one of "serial", "threaded", "mpl2005" or "mpl2014", default "serial".

  • corner_mask (bool, optional) – Enable/disable corner masking, which only has an effect if z is a masked array. If False, any quad touching a masked point is masked out. If True, only the triangular corners of quads nearest these points are always masked out, other triangular corners comprising three unmasked points are contoured as usual. If not specified, uses the default provided by the algorithm name.

  • line_type (LineType or str, optional) – The format of contour line data returned from calls to lines(), specified either as a LineType or its string equivalent such as "SeparateCode". If not specified, uses the default provided by the algorithm name. The relationship between the LineType enum and the data format returned from lines() is explained at Line type.

  • fill_type (FillType or str, optional) – The format of filled contour data returned from calls to filled(), specified either as a FillType or its string equivalent such as "OuterOffset". If not specified, uses the default provided by the algorithm name. The relationship between the FillType enum and the data format returned from filled() is explained at Fill type.

  • chunk_size (int or tuple(int, int), optional) – Chunk size in (y, x) directions, or the same size in both directions if only one value is specified.

  • chunk_count (int or tuple(int, int), optional) – Chunk count in (y, x) directions, or the same count in both directions if only one value is specified.

  • total_chunk_count (int, optional) – Total number of chunks.

  • quad_as_tri (bool) – Enable/disable treating quads as 4 triangles, default False. If False, a contour line within a quad is a straight line between points on two of its edges. If True, each full quad is divided into 4 triangles using a virtual point at the centre (mean x, y of the corner points) and a contour line is piecewise linear within those triangles. Corner-masked triangles are not affected by this setting, only full unmasked quads.

  • z_interp (ZInterp or str, optional) – How to interpolate z values when determining where contour lines intersect the edges of quads and the z values of the central points of quads, specified either as a ZInterp or its string equivalent such as "Log". Default is ZInterp.Linear.

  • thread_count (int) – Number of threads to use for contour calculation, default 0. Threads can only be used with an algorithm name that supports threads (currently only name="threaded") and there must be at least the same number of chunks as threads. If thread_count=0 and name="threaded" then it uses the maximum number of threads as determined by the C++11 call std::thread::hardware_concurrency(). If name is something other than "threaded" then the thread_count will be set to 1.

Returns:

ContourGenerator.

Note

A maximum of one of chunk_size, chunk_count and total_chunk_count may be specified.

Warning

The name="mpl2005" algorithm does not implement chunking for contour lines.