Line chart

basic

line

time-series

Time series visualization with proper date scaling

Line charts are ideal for showing trends over time. The SCALE x VIA date clause ensures proper date formatting on the axis.

Code

SELECT Date, Temp FROM ggsql:airquality
VISUALISE Date AS x, Temp AS y
DRAW line
SCALE x VIA date
LABEL
  title => 'Daily Temperature',
  x => 'Date',
  y => 'Temperature (F)'

Explanation

SELECT ... FROM ggsql:airquality queries the built-in air quality dataset
VISUALISE Date AS x, Temp AS y maps the date column to x and temperature to y
DRAW line connects data points with lines
SCALE x VIA date ensures the x-axis is formatted as dates with appropriate tick marks (happens automatically if your database has a dedicated date type)
LABEL provides descriptive titles for the chart and axes

Variations

Multiple lines by category

Here we show the temperature by day instead, and split the lines by month. Since month is encoded as an integer it doesn’t automatically split the lines, and we have to use an explicit ordinal scale for it (see what happens if you remove that).

SELECT Day, Temp, Month FROM ggsql:airquality
VISUALISE Day AS x, Temp AS y, Month AS color
DRAW line
SCALE ORDINAL color
LABEL
  title => 'Daily Temperature by Month',
  x => 'Date',
  y => 'Temperature (F)'