Use of functions on ipyaladin widgets

from ipyaladin import Aladin

Home-made functions

Let’s first write our own functions to apply to a generated sky view. We want to print the clicked object coordinates and informations.

aladin = Aladin(
    survey="P/DSS2/red",
    fov=10,
    target="LMC",
    reticle_color="#ff89ff",
    show_status_bar=True,
)
aladin

url = (
    "https://vizier.unistra.fr/viz-bin/votable?-source=HIP2&-c=LMC&-out.add=_RAJ,_"
    "DEJ&-oc.form=dm&-out.meta=DhuL&-out.max=9999&-c.rm=180"
)
options = {"source_size": 12, "color": "#f08080", "on_click": "showTable"}
aladin.add_catalog_from_URL(url, options)

After clicking on a source, you can print its value with:

aladin.clicked_object

{}

def get_object_data(data: dict) -> dict:
    """Print the clicked object data.

    Parameters
    ----------
    data : dict
        The data of the clicked object.
    """
    print("It clicked.")
    return data


def get_object_ra_dec_product(data: dict) -> float:
    """Return the product of the ra and dec values of the clicked object.

    Parameters
    ----------
    data : dict
        The data of the clicked object.
    """
    return data["ra"] * data["dec"]


# when triggered, the listeners on the js side of the application will send a
# json object whose parameter data will be used by the python functions
# (data is a literal object on the js side, it will be converted as a dictionary
# object on the python side)
aladin.set_listener("object_hovered", get_object_ra_dec_product)
aladin.set_listener("object_clicked", get_object_data)

Built-in methods

The Aladin object also comes with its built-in methods. Here we illustrate one of them.

aladin_bis = Aladin(target="269.956288 -23.823863", fov=1)
aladin_bis

aladin_bis.set_color_map("redtemperature")

Save the view as an image

aladin_bis.save_view_as_image("4Sgr.png")