Show data: tables and charts

Numbers on a slide can be a table, a bar chart, a line, a few large figures or a grid of colours. You write the numbers once; one word decides how they look, and the theme and palette decide the colours.

The easiest way is to ask your assistant:

Ask your assistant

Turn the table on page 4 of results.pdf into a bar chart on its own
slide, and highlight this year.

Write the numbers#

Put the numbers between <data> and </data>, one row per line, the names of the columns first:

Example

<data show="bar" title="Students per year" highlight="2024">
year, students
2021, 120
2022, 148
2023, 161
2024, 203
</data>

This is CSV, the format spreadsheets save as. Separate the cells with commas, or with semicolons or tabs, as Excel often does. Write numbers without thousands separators (1234, not 1,234), with a point or a comma before the decimals: 7.1 or 7,1. In a file separated by commas, a number with a comma goes in double quotes: "7,1". The slides show numbers as your deck's language writes them. A cell that contains a comma goes in double quotes: "Smith, J.".

Numbers you keep in a spreadsheet can stay there. Save it as CSV beside the slides and name the file:

Example

<data src="enrolment.csv" show="line" />

The file travels with the deck when you send it or make a PDF. While mdeck run shows the slides, saving the file shows the new numbers.

Choose how it looks#

show picks the way. Without it, the data is a table.

`show`	Good for
`table`	Exact values, a few rows; numbers line up on the right
`bar`	Comparing amounts: years, groups, places. Long names turn the columns into bars
`line`	Change over time, one line per column of numbers
`scatter`	Two measurements against each other, such as rainfall and yield
`stat`	One to four numbers the slide is about, large
`heatmap`	A grid of numbers, such as results per group and week, or correlations
`dumbbell`	Two values per row: before and after, two groups

Change show="bar" to show="line", and the same numbers become a line.

Pick out what matters#

highlight="2024" picks out a row: in a chart the other bars fade, in a table the row is marked.
y="wheat, barley" shows only these columns; x="region" says which column names the rows.
sort="students desc" puts the largest first; rows="1-5" keeps the first five (after sorting: the top five).
title="…" writes a title above, unit="t" names the unit, caption="Source: Federal Statistical Office" writes a line below.
steps="rows" shows one row per click, steps="series" one column of numbers per click, as points do with :::steps.

Each way of showing has a few settings of its own, written like the others; mdeck list dataviews lists them:

`show`	Settings
`table`	`max-rows="8"` (the rest are counted below), `numbers="formatted"` (your language's separators instead of the numbers as written)
`bar`	`orientation="horizontal"` (or `vertical`), `stacked`, `values="all"` (or `highlight`, `none`), `max` (the axis ends there; taller bars are cut off), `min` (0 or below: bars always start at 0)
`line`	`points="all"` (or `none`), `fill` (for one line), `zero` (the axis starts at 0), `min`, `max` (the axis starts and ends there)
`scatter`	`labels="site"` (a column that names the points), `zero`
`stat`	`change="change"` (a column with each figure's change)
`heatmap`	`values="false"` (no numbers in the cells), `scale="diverging"` (two colours either side of 0), `min`, `max`
`dumbbell`	`values="false"`, `zero`

Good charts on slides#

One message per chart: say it in the slide's heading ("Enrolment doubled since 2021"), and highlight the part that shows it.
Two or three columns of numbers at most. The palette has three accent colours; after that, colours get hard to tell apart, and mdeck check says so.
For a few exact numbers, a table or stat is often clearer than a chart.
Hotspots (hotspots: auto) let you zoom into a chart while you talk.

If something is wrong, such as a misspelled column name or a cell that is not a number, the slide says what instead of the chart, and so does mdeck check.

Want a kind of chart mdeck does not have? Ask your assistant for a new dataview; it keeps it in the deck's extensions folder. See Create a dataview.