Allison Horst

Observable

Custom theme elements for reuse in Observable Plot

Paul Buffa

Data wrangling essentials: comparisons in JavaScript, Python, SQL, R, and Excel

Descriptive statistics: comparisons in JavaScript, Python, SQL, R, and Excel

Life in a waffle chart

Build a simple interactive Gantt chart

Simple linear regression

Getting started with Observable? You’ve come to the right place.

Tutorials

Workflow Resources

Collection of notebooks related to data science in Observable

Data Science in Observable

Data Analysis

New to wrangling data in JavaScript? This notebook walks through common data manipulations across several languages so you can learn how to do your data workflows in JS.

Staff Picks: Data Wrangling Essentials 

Examples of how Data Scientists are using Observable

Data Science 

Rather than hardcoding the column names, how can one specify column names through a variable? Let's say from a checkbox input for example.

Roy Francis

Sure! You could do something like have one cell like this:

columns = ['a', 'b', 'c', 'd']

And then the map would be:

myData.map(d => ({...columns.map(e => d[e])}) )

You could use checkbox input for the "columns" cell so its interactive. I can make a quick example if this doesnt make sense :)

Thanks! This was helpful. I would love to see a full realistic analysis workflow. For example; Read in a csv file, capture the column names as a variable, filter columns to keep, then select columns to filter by rows (categorical and numeric filtering) with input widgets and all that through variable without any hard coded values. ie; it should work with any random csv file.

You got it! This should accomplish what you're looking for https://observablehq.com/d/55dd0fe0f276ccfd

The function `d3.rollup` returns a Map, which does not allow for further reference to the elements, by their names. How to deal with that if I want to do some more grouping or other wrangling afterwards?

JuliaR

Good question! You can use d3.flatRollup or d3.rollups instead to return an array. Combined with map (as shown here: https://observablehq.com/@d3/d3-flatgroup#cell-54), this will get your grouped values back into a 2D array that you can continue with.