md`# My first exercise is only about data!`
d3 = require("d3@5")
topojson = require("topojson-client@3")
states = FileAttachment("dtl_cnty.json").json()
states_features = topojson.feature(states, states.objects.dtl_cnty)
csv_data = d3.csvParse(await FileAttachment("dtl_cnty.csv").text(),({FIPS, POPULATION, SQMI}) => [+FIPS, [+POPULATION/+SQMI]])
//this is how to take the values of a variable (column) from all variables you created from the csv file
popdensity = Array.from(csv_data.values(), d => d[1])
//this is how you map the id column to the values. We will use this for joining with topojson later.
data = Object.assign(new Map(csv_data), {title: ["Females", "Female Pct"]})
Purpose-built for displays of data
Observable is your go-to platform for exploring data and creating expressive data visualizations. Use reactive JavaScript notebooks for prototyping and a collaborative canvas for visual data exploration and dashboard creation.
