Tzong Hao Chen tzonghao

One-line Tree in Python

Using Python's built-in defaultdict we can easily define a tree data structure:

def tree(): return defaultdict(tree)

That's it!

This is in response to https://peadarcoyle.wordpress.com/2016/03/02/a-map-of-the-pydata-stack/ . It started off as an e-mail but I decided to keep things public.

First, let me just say that I think that reproducing the ML decision graph is a really cool idea. I suspect that it'll get hairy for a while as people speak up. I'll speak up below, but I'm obviously invested in some of these projects, so you should probably take everything I say with a grain of salt. OK, here we go:

To me scientific data overlaps with tabular and array. It's not clear that the choice between {array, dataframe, scientific} is easy to make "Well, I have scientific array data, what do I choose now?"

The same issue exists somewhat for time-series "Well, I have tabular time series, which branch do I take?" I recommend removing Castra from the map, it's not a very serious project.

I can envision a separate map for storage technologies (hdf5, netcdf, bcolz, castra, csv, parquet, ...) It's odd to have both computational system

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	from django import forms
	from django.contrib.postgres.fields import ArrayField


	class ChoiceArrayField(ArrayField):
	"""
	A field that allows us to store an array of choices.

	Uses Django 1.9's postgres ArrayField
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	height: 760
	license: gpl-3.0