Weekly chart of how a metric has moved

Every Monday this workflow reads the measurement history you keep in a Google Sheet, draws the measure you name as a line chart, and emails you the chart with a short note on how the numbers have moved. A column of figures tells you where you are; the shape of the line tells you what has been happening, which is the part a weekly read is actually for.

The note is written from the charted readings and nothing else. It is told to describe only what the readings show - not to forecast, not to set a target, not to advise, and not to explain why anything moved, because a list of numbers cannot tell you that. The readings are printed underneath, so nothing in the note has to be taken on trust.

The tab it reads has one row per reading, with Period, Measure and Value columns, oldest at the top. Value can be written however your sheet writes it - 1,240 or $1,240 or 18% all read fine - and a row whose value holds no number at all is listed as left off rather than counted as a zero. Commas are taken out of the period names before charting, because the chart treats a comma as the start of the next label.

The email carries a permanent link to the chart image rather than the image itself, so the picture is one click away and stays reachable afterwards.

Only the most recent 24 readings are charted; past that the labels along the bottom overlap into a smear. Raise 'maxPoints' if you want a longer run and can live with a busier axis. If the chart cannot be drawn the readings are still emailed on their own.

To set it up, paste the spreadsheet URL, name the measure to chart, and give the address to send to.