Customizing your dual-axis chart

This article explains how you can customize a dual-axis chart in Datawrapper after you uploaded your dataset to Datawrapper and selected the dual-axis chart type.

This article uses the following chart as an example, but covers all customization options in the process:

Contents

1. Refine: Display options
   • Changing which data series appears on which Y axis
   • Changing the chart type of your data series
   • Line chart options
   • Column chart options
   • Area chart options
2. Refine: Vertical axis
   • Left / Right side
   • Both sides
3. Refine: Horizontal axis
4. Refine: Legend
5. Refine: Appearance
6. Refine: Tooltips
7. Annotate
8. Annotate: Text annotations
9. Annotate: Highlight range
10. Layout & Publish

In Step 3: Visualize, you'll notice three tabs besides Chart type: Refine, Annotate, and Layout. Let's start with what's in the Refine tab.

Refine: Display options

In this first section of the Refine tab, you can choose which of your columns should be displayed as column charts, line charts, and area charts, and you can customize the color and style of those chart types.

Changing which data series appears on which Y axis

Let's look at the Display options in detail. Datawrapper shows you a little table with two sides, and all your numeric columns (= "data series") you uploaded. Every data series on the left side will use a the left-hand Y axis. Every data series on the right side will use the right-hand Y axis:

By default, the first numeric column in your data is on the left side and shown as a column chart, and all other numeric columns are on the right side, shown as lines. But you can change both the chart type and why Y axis it uses:

You can move a data series to another side. Either drag and drop one or more list items from one side to the other (to select multiple ones, hold Shift); or select a list item and and then use the little arrow in the middle of the table to move it to the other side; or hover over a list item and then click on the little arrow that appears. The following video shows all three options:

You can also flip all data series or the whole chart. To do so, make sure no item is selected (just click on a selected item to deselect it). Then click on the little swap button in the middle of the table. This will flip all data series from one side to the other. If you press the Alt/Option key while clicking the button, the whole chart will flip (including the chart types), not just the data series. Here are both options:

Changing the chart type of your data series

At the top of each side in the table, you can choose the chart type in which all data series on that side will be displayed. Simply click on either the symbol for the column chart, area chart, or line chart.

You can display the following chart types in a Datawrapper dual-axis chart:

• Line chart with one or multiple lines

• Area chart with one or multiple areas, either stacked, 100% stacked, or unstacked

• Column charts with one or multiple columns, either stacked, 100% stacked, or grouped

You will see different options depending on the number of data series you want to show on one side. Here's an example:

If you have more than one data series on one side, you can click on the a certain data series to change the chart options (e.g. the color of an area). To change the "global" chart options for all data series on that side (e.g. to decide if the areas are stacked or not), click on Column/Area/Line styles at the top of all your data series.

Let's go through the options available for each chart type:

Line chart options

Here are the available options for line charts.

• Color lets you choose the color of the line. As a global setting, this option will appear as Base color, which lets you choose the color of which shades will be applied to all lines.
• Show outline adds a very fine stroke around your line in the color of the chart background. This makes it easy to distinguish between lines if they overlap a lot
• Interpolation allows you to control how the lines are connected between the data points. To read more about when to choose which interpolation, visit our blog post.
• Width and Dash allow you to define exactly that: how thick your line should be, and if it should be dashed. If you click on the last Width option, you can make your line disappear. This setting only exists for individual lines.
• Label: Here you can decide how your data series should be called in both the tooltip and the color legend. "Show in legend" is turned on by default. If you turn it off, the label will only appear in the tooltip. This setting only exists for individual lines.
• Show value labels: Toggling this on show labels close to your line that tell readers which numeric values your line(s) show. Now you can customize the number format, decide if you want to label all first or last values of a line, decide how many value labels should be visible per line, add little circles to the lines that make clearer which data points are labeled (Outline labeled data points), or use the line color for the value labels. You can learn more about value labels in line charts on our blog.
• Show line symbols: The next option you have is to add little circles/triangles/squares etc. to your lines to highlight each data point, or just the beginning and/or end of each line. You can decide on
  • the kind of symbol (circle, square, diamond, triangle, cross, hexagon, star, or wye)
  • if the symbols should show up on the first and/or last, or on all data points. (Showing them on all data points only makes sense if you have few data points per line.)
  • the style: filled ● or hollow ○
  • the size (how big should the circles be?)
  • and their opacity (how transparent should they be?)
• Connect all points: If your uploaded data is missing some data points, you can use this option to fill the line between data points that have gaps between them, though consider that interpolating missing data can be misleading, as it may suggest that your dataset has more values than it actually does. Learn more about this feature here.

Here's a video in which we adjust the line chart settings for our chart:

Column chart options

These are the chart type options for a column chart.

• Color lets you choose the color of the columns. For >1 data series, this option will appear as Base color, which lets you choose the color of which shades will be applied to all columns.
• Space between columns specifies how thick or thin you want the columns to be, in % of the column width. You can change the column gap from 0% (no gap at all) to 100%.
• Label: Here you can decide how your data series should be called in both the tooltip and the color legend. "Show in legend" is turned on by default. If you turn it off, the label will only appear in the tooltip. This setting only exists for individual data series.
• Stack columns [for >1 data series] lets you turn your columns from a grouped column chart to a stacked column chart. You have the choice to sort the columns (smallest first, largest first) or to stack your columns to 100%.
• Show value labels: Toggling this on will give your the further options of setting the number format, placement (inside or outside of the columns), whether they should match the color of the column and whether overlapping labels should be hidden so they remain legible.
• Show totals: If you stack your columns, you get the option to show the sum of all stacked columns above the highest one.
• Number format: Lets you choose the number format for both value labels and totals, whatever you have turned on.
• Label overlap: Turn on Prevent label overlapping to make sure that labels hide when they would otherwise overlap.

Here's a video demonstrating some of the column chart options (with another data set this time). Note that options become available and unavailable depending on the decisions you make on the way – e.g. if you want your columns stacked or unstacked:

Area chart options

If you choose an area chart for one or multiple data series,

• Color lets you choose the color of the areas. For >1 data series, this option will appear as Base color, which lets you choose the color of which shades will be applied to all areas.
• Interpolation allows you to control how the areas are connected between the data points. To read more about when to choose which interpolation, visit our blog post.
• Area opacity defines how transparent the area fill should be. You can move the slider or type in a number between 0 (very transparent) or 1 (not transparent at all).
• Label: Here you can decide how your data series should be called in both the tooltip and the color legend. "Show in legend" is turned on by default. If you turn it off, the label will only appear in the tooltip. This setting only exists for individual data series.
• Stack areas [for >1 data series]: Stacking means that all areas sit separately on top of each other. If you deselect this setting, all areas will lay behind each other. This is harder to read and only a great option in a few cases, so "Stack areas" is selected by default in our tool. You have the choice to sort the areas (smallest first, largest first) or to stack your columns to 100%. You can also choose to display a fine line between all your areas, and pick the color of this line.

Refine: Vertical axis

The next section covers everything related to your vertical axes, both left and right.

At the very top, you can choose your Tick alignment. This adjusts the range of both axis, so the left- and right-side tick marks are horizontally aligned or independent of each other. Use Independent to let each axis fill its space or use a custom range. Using Aligned ticks adjusts the scales so grid lines line up across both axes for a cleaner look. This may add space at the top or bottom and can influence the look of the chart depending on the chart height.

If you choose an independent tick alignment, one of the Grid options (see below) must be Ticks. If you choose Lines for both the left and right side, one of them will fall back to Ticks.

If you choose aligned ticks, the Grid options of the left and right side must be the same. Whatever you choose for the left side (either Lines or Ticks) will also apply to the right side, and the other side round. That said, you can have ticks on one side and no grid whatsoever on the other side. Also, with aligned ticks, you won't be able to set custom ticks anymore in the settings below.

Left / Right side

The next two subsections offer the same customization options, so we’ll cover what each one does in one go:

• Custom range changes the axis range based on the inputted minimum and maximum values. By default it encompasses the lowest and highest values in your dataset and setting the minimum to a value greater than zero will be ignored when using columns.
• Custom ticks: By default, Datawrapper tries to find a good-looking number of gridlines it then labels. You can change that by adding your own values, separated by a comma. Note that values will only be shown if they don’t overlap and fall within the custom range. Also note that custom ticks aren't available when you chose an aligned tick alignment above.
• Number format: Choose how your numbers should appear (e.g. 18,000 or 18000 or 18K). Learn about the available options in this Academy article.
• Prepend/append enables you to add text or symbols in front or behind your values, e.g. a $ or € sign, letters or words like “jobs created”, or a combination of the two, like °C.
• Grid: By default, horizontal grid lines are shown. You can decide to switch them off or to only show ticks next to grid labels. Note that when scales are aligned, both sides update together to keep the grid style consistent.
• Grid labels: By default, grid labels are shown, but they can also be switched off.

Both sides

The settings in this subsection affect both axes:

• Label position: You can decide to display your grid labels outside (= to the left, in left-to-right charts) or inside of the chart body. If you have set grid labels to be hidden on both axes, this option will be unavailable.
• Label color: Here you have the option to match the color of your grid labels to the color of the data series or to use a neutral color instead. In general, we recommend keeping this option toggled on so that it is easier for readers to match a data series with the correct axis. If an axis has multiple data series with a mix of different colors, the grid labels will automatically assume a neutral color. If you have set grid labels to be hidden on both axes, this option will be entirely unavailable.
• Scale alignment: This tick box allows you to make scales proportional, meaning the range of the dataset will be adjusted to make the axis proportional to each other. This can help reduce any overfitting of correlated trends.

If you show only lines in your chart and at least one of your y-axes doesn't start at zero, you'll also see the option to improve the comparability by aligning axis scales. What does this mean? Well, if one of your axes grows by 20% (e.g. from 50 to 60), while the second line grows by 80% (from 400k to 720k), then your scales are not proportional – and your chart is probably misleading:

When you align the covered share of your two axes, readers can actually compare the growth of your data series, very similar to an indexed chart. We strongly recommend turning this feature on.

Refine: Horizontal axis

Similar to the settings for the vertical axis, the settings for the horizontal axis let you define the range, ticks, and grid appearance:

• Custom range allows you to explicitly extend and truncate the horizontal axis to custom values.
• Custom ticks allows setting custom axis ticks for the horizontal grid lines. Ticks need to be separated by comma.
• Date format: By default, Datawrapper tries to guess which date format could work best for your data – in our case, that's why years show up. Here's an overview of all date formats Datawrapper can display.
• Grid: Here you can decide if you’d rather show gridlines running from the top to the bottom of your chart, ticks (= short marks below the axis), or no grid at all.

Refine: Legend

Here you can decide to show axis titles and a color key.

First, you see a toggle to turn on axis titles. Axis titles let you add a title above the left and/or the right y-axis. They're an extra way to describe what your axes show.

By default, the color of those axis titles match the colors of the chart elements – e.g. if you have a red area chart, the axis title will be red, too. If all the areas in your stacked area chart are green-ish, a green title will be shown. Black, gray, or white (in dark mode) is used for a title if the chart elements are using a mix of different colors. To let axis title appear black or white, uncheck Match color to chart elements.

In addition to or instead of the axis titles, you can display a color legend in your chart:

By default, a color legend is always turned on. You can choose a layout, decide to show the items as a list (meaning, stacked/below each other), and to add axis side labels ("Left scale:" and "Right scale"). Let's go through all the available options:

• Selecting Split places the labels of each data series above their respective sides. All of the series labels that belong to the left side will be shown above the left axis, while right-side labels are shown next to each other above the right axis. Same-axis labels can also be shown next to or below each other using the Show items as list tick box underneath the Layout selector.
• Selecting Stacked positions legend entries on the left-hand side, with series labels from the left side placed above the right-side labels. The labels can also be listed next to or below the side keys (i.e. ”left scale”, “right scale”) using the Show items as list tick box underneath the Layout selector.
• Selecting Combined means that all legend entries will be shown inline from left to right.

Axis side labels (”Left scale” and “Right scale”) are turned on by default, but they can also be switched off. In the Split layout, the On option is replaced with Auto, meaning side keys are not shown unless the chart is so narrow that the legend entries from either side begin to overlap.

Here are a few options in practice:

If you enable Highlight series on hover, your readers can hovering over a legend entry to highlight the corresponding data series in the chart.

Refine: Appearance

Here you can decide on the height and the size of the margin of your chart.

You can set a fixed plot height, or one based on width that scales with the width of your chart. To learn more about the concept of chart resizing and the difference between fixed and width-based plot height, visit this Academy article.

Refine: Tooltips

By default, Datawrapper dual-axis charts will show tooltips: if your readers hover over your chart, they will see the underlying values for all data series at the corresponding position.

In the Tooltips panel, you can turn that behavior off. If you leave it turned on, you change the number format of the values displayed for the left, right and horizontal axis. You can also choose if you want the horizontal axis data point to be shown on the horizontal axis (see screenshot above), or as the title of the tooltip (the default, see below:):

After working through all these options in the  Refine tab, let's move on to the next tab: Annotate.

Annotate

After working through all these options in the Refine tab, let's move on to the next tab: Annotate.

In the Annotate tab, you're first asked to give your visualization a title, description, notes, source, byline, and an alternative description for screen readers. You can find a detailed explanation of all these Annotate options here.

Annotate: Text annotations

The next section lets you add and customize text annotations anywhere on your dual-axis chart. It's a really powerful tool, so we wrote an extra article about it. Learn how to create text annotations here.

What's special about text annotations in dual-axis charts is that you can assign the annotation to an axis (Axis: Left/Right), and use the axis color (in the Text style options). If you switch the axis in the Refine tab, the annotations will switch, too.

Annotate: Highlight range

Finally, if you want to draw your reader's attention to one specific time range, the Highlight range tool is perfect. It lets you set semi-transparent colored overlays and lines directly in your chart. To do so, click on Add range highlight. Now select a starting and ending point of the range by clicking in the chart. If you want, you can also change the opacity of the highlighted range. Here's an in-depth explanation of all the options.

Layout & Publish

After adding text to our chart, only one tab is left in step 3: Visualize: The Layout tab. You can find all Layout settings explained in this Academy article. And once you're happy with your settings, it's time to publish! We prepared another detailed Academy article about publishing, embedding, and exporting your chart here.

And that's it! You successfully customized your first dual-axis chart.