deltametrics.mask.EdgeMask

class deltametrics.mask.EdgeMask(*args, **kwargs)

Identify the land-water edges.

An edge mask object, delineates the boundaries between land and water. Edge identification is implemented via Canny edge detection from skimage (skimage.feature.canny).

Examples

Initialize the edge mask from elevation data:

golfcube = dm.sample_data.golf()
edgmsk = dm.mask.EdgeMask(
    golfcube['eta'][-1, :, :],
    elevation_threshold=0)

fig, ax = plt.subplots(1, 2, figsize=(8, 4))
golfcube.quick_show('eta', idx=-1, ax=ax[0])
edgmsk.show(ax=ax[1])
plt.show()

(png, hires.png)

__init__(*args, **kwargs)

Initialize the EdgeMask.

Initializing the edge mask requires either a 2-D array of topographic data, or it can be computed using the LandMask and the WetMask.

Parameters:

• arr (ndarray) – The data array to make the mask from.

• contour_threshold (int, optional) –

  Threshold value used for identifying the shoreline.

  Default threshold opening angle used in the OAM. Default is 75 degrees. Could also be a value between 0-1 in the case of the MPM.

• is_mask (bool, optional) – Whether the data in arr is already a binary mask. Default value is False. This should be set to True, if you have already binarized the data yourself, using custom routines, and want to just store the data in the EdgeMask object.

• landmask (LandMask, optional) – A LandMask object with the land identified

• wetmask (WetMask, optional) – A WetMask object with the surface water identified

• kwargs (optional) – Keyword arguments for compute_shoremask.

Methods

__init__(*args, **kwargs)	Initialize the EdgeMask.
from_Planform(_Planform, **kwargs)	Create EdgeMask from a Planform.
from_Planform_and_WetMask(_Planform, ...)	Create from a Planform and a WetMask.
from_array(_arr)	Create an EdgeMask from an array.
from_mask(*args, **kwargs)	Create a EdgeMask directly from a LandMask and a WetMask.
from_masks(*args, **kwargs)
show([ax, title, ticks, colorbar])	Show the mask.
trim_mask(*args[, value, axis, length])	Replace a part of the mask with a new value.

Attributes

integer_mask	Binary mask values as integer
mask	Binary mask values.
mask_type	Type of the mask (string)
shape
variables

__getitem__(var)

Implement slicing.

Return values directly from the mask. Supported variables are only ‘mask’ or ‘integer’.

static from_Planform(_Planform, **kwargs)

Create EdgeMask from a Planform.

static from_Planform_and_WetMask(_Planform, _WetMask, **kwargs)

Create from a Planform and a WetMask.

Important

This instantiation pathway should only be used for custom WetMask implementations, where the below_mask from the OpeningAnglePlanform is not sufficient to capture the wet area of the delta.

Hint

To create an EdgeMask from an existing WetMask and LandMask, see the static method from_mask.

Examples

static from_array(_arr)

Create an EdgeMask from an array.

Note

Instantiation with from_array will attempt to any data type (dtype) to boolean. This may have unexpected results. Convert your array to a boolean before using from_array to ensure the mask is created correctly.

Parameters:

_arr (ndarray) – The array with values to set as the mask. Can be any dtype but will be coerced to boolean.

static from_mask(*args, **kwargs)

Create a EdgeMask directly from a LandMask and a WetMask.

property integer_mask

Binary mask values as integer

Important

integer_mask is a boolean array as 0 and 1 (integers). It is not suitible for multidimensional array indexing; see also mask.

Read-only mask attribute.

Type:

ndarray

property mask

Binary mask values.

Important

mask is a boolean array (not integer). See also integer_mask.

Read-only mask attribute.

Type:

ndarray

property mask_type

Type of the mask (string)

show(ax=None, title=None, ticks=False, colorbar=False, **kwargs)

Show the mask.

The Mask is shown in a matplotlib axis with imshow. The mask values are accessed from integer_mask, so the display will show as 0 for False and 1 for True. Default colormap is black and white.

Hint

Passes **kwargs to matplotlib.imshow.

Parameters:

ax (matplotlib.pyplot.Axes) – Which axes object to plot into.

trim_mask(*args, value=False, axis=1, length=None)

Replace a part of the mask with a new value.

This is sometimes necessary before using a mask in certain computations. Most often, this method is used to manually correct domain edge effects.

Parameters:

• *args (BaseCube subclass, optional) – Optionally pass a Cube object to the mask, and the dimensions to trim/replace the mask by will be inferred from the cube. In this case, axis and length have no effect.

• value – Value to replace in the trim region with. Default is False.

• axis – Which edge to apply the trim of length to. Default is 1, the top domain edge.

• length – The length of the trim. Note that this is not the array index.

Examples