ipylazylink

Lazy file link widget for Jupyter

Motivation

When you present results in a notebook, you may want to allow users to download these results on their computer, typically in CSV or Excel format. In order to do this you would add to your notebook a link that points to a file, using something like FileLink. The problem with this approach is that the file must already exist, so you need to generate the file even if users never download it. When this file generation takes time and you have several such links, it can significantly slow down execution of your notebook for something that might never be used.

The LazyLink widget aims at solving this problem by providing a link to a file that doesn't exist yet: a lazy link. The file gets created on-demand by a callback function that you provide. That function must return the path to the file that it creates.

Usage

from ipylazylink import LazyLink

def create_file():
    time.sleep(2)  # Simulate slow computation
    filepath = "output.csv"
    with open(filepath, "w") as fp:
        fp.write("file content")
    return filepath

w = LazyLink(text="Download results as CSV")
w.on_click(create_file)

Installation

To install using pip:

$ pip install git+https://github.com/weatherforce/ipylazylink.git
$ jupyter nbextension enable --py --sys-prefix ipylazylink

For a development installation (requires npm):

$ git clone https://github.com/weatherforce/ipylazylink.git
$ cd ipylazylink
$ pip install -e .
$ jupyter nbextension install --py --symlink --sys-prefix ipylazylink
$ jupyter nbextension enable --py --sys-prefix ipylazylink