ArrowHead

The ArrowHead class encapsulates the arrow head at the end of a Curve in a Reaction. It provides methods to retrieve and modify the arrow head’s identifier, bounding box position and size, and any underlying geometric shapes and styling.

After loading a model and retrieving a Curve in a Reaction, you can:

Obtain the ArrowHead instance via Curve.get_arrow_head().
Inspect or update its position, size, shapes, and styling.

import sbmlnetwork as sn

# Load the SBML model
net = sn.load("my_model.xml")

# Get reaction id
reaction_id = net.get_reaction_ids()[0]

arrow_head = None

# Find the first species that is a product of the reaction
for species in net.get_species_list():
    if species.get_role(reaction_id) == "product":
        arrow_head = species.get_arrow_heads()[0]
        break

# Inspect identifier and position
print("ID:", arrow_head.get_id())
print("Position:", arrow_head.get_relative_position())

Core Methods

Identification

get_id()

Return the unique identifier of the arrow head (start or end), or None if not defined.

Return type:: str or None

Position

get_relative_position()

Get the (x, y) coordinates of the arrow head’s bounding box.

Returns:: A 2-tuple of floats representing (x, y).
Return type:: tuple[float, float]

set_relative_position(relative_position)

Set the (x, y) coordinates of the arrow head’s bounding box.

Parameters:: relative_position (tuple[float, float]) – A 2-tuple of floats representing the new (x, y).
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

Size

get_size()

Get the (width, height) of the arrow head’s bounding box.

Returns:: A 2-tuple of floats representing (width, height).
Return type:: tuple[float, float]

set_size(size)

Set the (width, height) of the arrow head’s bounding box.

Parameters:: size (tuple[float, float]) – A 2-tuple of floats representing the new (width, height).
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

Shapes

add_shape(shape_type)

Add a new geometric shape of the given type to this arrow head.

Parameters:: shape_type (str) – One of the valid geometric shape type names.
Returns:: The newly created ShapeBase instance, or None if creation failed.
Return type:: ShapeBase or None

remove_shape(shape)

Remove the specified shape from this arrow head.

Parameters:: shape (ShapeBase) – The ShapeBase to remove.
Returns:: True if removal succeeded, False otherwise.
Return type:: bool

get_shape()

Retrieve the first geometric shape attached to this arrow head.

Returns:: A ShapeBase or None if no shapes are present.
Return type:: ShapeBase or None

get_shapes_list()

Return a list of all geometric shapes attached to this arrow head.

Returns:: A ShapeList containing all shapes.
Return type:: ShapeList

get_shape_type()

Get the types of all attached geometric shapes.

Returns:: A list of shape type names.
Return type:: list[str]

Styling

get_border_color()

Get the border color(s) of all attached shapes.

Returns:: A list of color values.
Return type:: list[str]

set_border_color(border_color)

Set the border color for all attached shapes.

Parameters:: border_color (str) – A color string (e.g., “#RRGGBB”).
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

get_border_thickness()

Get the border thickness(es) of all attached shapes.

Returns:: A list of floats.
Return type:: list[float]

set_border_thickness(thickness)

Set the border thickness for all attached shapes.

Parameters:: thickness (float) – The new border thickness.
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

get_fill_color()

Get the fill color(s) of all attached shapes.

Returns:: A list of color values.
Return type:: list[str]

set_fill_color(fill_color)

Set the fill color for all attached shapes.

Parameters:: fill_color (str or tuple or list) – A color string or RGB tuple/list.
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

Movement

move_relative_position_to(relative_position)

Alias for set_relative_position().

Parameters:: relative_position (tuple[float, float]) – A 2-tuple of floats representing the new (x, y).
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

move_relative_position_by(delta)

Move the arrow head by the specified (dx, dy) offset.

Parameters:: delta (tuple[float, float]) – A 2-tuple of floats representing (dx, dy).
Returns:: True if the operation succeeded, False otherwise.
Return type:: bool

Information

property info

Human-readable summary of glyph state for debugging.

Return type:: str

get_info(): Generate the info string.

Example workflow

import sbmlnetwork as sn

# Load the SBML model
net = sn.load("my_model.xml")

# Get an arrow head from the first reaction
curves = net.get_reactions_list()[0].get_curves_list()
arrow_head = None
for curve in curves:
 if curve.get_arrow_head() is not None:
     arrow_head = curve.get_arrow_head()
     break

# Inspect identifier and position
print("ID:", arrow_head.get_id())
print("Position:", arrow_head.get_relative_position())

# Resize and restyle
arrow_head.set_size((10.0, 8.0))
arrow_head.set_fill_color("#333333")
arrow_head.set_border_color("#000000")