From 696f3044ee6eeeba69abbbe46b7e714bc61a53dc Mon Sep 17 00:00:00 2001
From: sbosse <sbosse@uni-bremen.de>
Date: Mon, 21 Jul 2025 23:36:10 +0200
Subject: [PATCH] Mon 21 Jul 22:43:21 CEST 2025

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+# Cartesian Axes
+
+Axes that follow a cartesian grid are known as 'Cartesian Axes'. Cartesian axes are used for line, bar, and bubble charts. Four cartesian axes are included in Chart.js by default.
+
+* [linear](./linear.md#linear-cartesian-axis)
+* [logarithmic](./logarithmic.md#logarithmic-cartesian-axis)
+* [category](./category.md#category-cartesian-axis)
+* [time](./time.md#time-cartesian-axis)
+
+## Common Configuration
+
+All of the included cartesian axes support a number of common options.
+
+| Name | Type | Default | Description
+| ---- | ---- | ------- | -----------
+| `type` | `string` | | Type of scale being employed. Custom scales can be created and registered with a string key. This allows changing the type of an axis for a chart.
+| `position` | `string` | | Position of the axis in the chart. Possible values are: `'top'`, `'left'`, `'bottom'`, `'right'`
+| `offset` | `boolean` | `false` | If true, extra space is added to the both edges and the axis is scaled to fit into the chart area. This is set to `true` for a category scale in a bar chart by default.
+| `id` | `string` | | The ID is used to link datasets and scale axes together. [more...](#axis-id)
+| `gridLines` | `object` | | Grid line configuration. [more...](../styling.md#grid-line-configuration)
+| `scaleLabel` | `object` | | Scale title configuration. [more...](../labelling.md#scale-title-configuration)
+| `ticks` | `object` | | Tick configuration. [more...](#tick-configuration)
+
+### Tick Configuration
+The following options are common to all cartesian axes but do not apply to other axes.
+
+| Name | Type | Default | Description
+| ---- | ---- | ------- | -----------
+| `autoSkip` | `boolean` | `true` | If true, automatically calculates how many labels can be shown and hides labels accordingly. Labels will be rotated up to `maxRotation` before skipping any. Turn `autoSkip` off to show all labels no matter what.
+| `autoSkipPadding` | `number` | `0` | Padding between the ticks on the horizontal axis when `autoSkip` is enabled.
+| `labelOffset` | `number` | `0` | Distance in pixels to offset the label from the centre point of the tick (in the x direction for the x axis, and the y direction for the y axis). *Note: this can cause labels at the edges to be cropped by the edge of the canvas*
+| `maxRotation` | `number` | `50` | Maximum rotation for tick labels when rotating to condense labels. Note: Rotation doesn't occur until necessary. *Note: Only applicable to horizontal scales.*
+| `minRotation` | `number` | `0` | Minimum rotation for tick labels. *Note: Only applicable to horizontal scales.*
+| `mirror` | `boolean` | `false` | Flips tick labels around axis, displaying the labels inside the chart instead of outside. *Note: Only applicable to vertical scales.*
+| `padding` | `number` | `0` | Padding between the tick label and the axis. When set on a vertical axis, this applies in the horizontal (X) direction. When set on a horizontal axis, this applies in the vertical (Y) direction.
+
+### Axis ID
+The properties `dataset.xAxisID` or `dataset.yAxisID` have to match the scale properties `scales.xAxes.id` or `scales.yAxes.id`. This is especially needed if multi-axes charts are used.
+
+```javascript
+var myChart = new Chart(ctx, {
+    type: 'line',
+    data: {
+        datasets: [{
+            // This dataset appears on the first axis
+            yAxisID: 'first-y-axis'
+        }, {
+            // This dataset appears on the second axis
+            yAxisID: 'second-y-axis'
+        }]
+    },
+    options: {
+        scales: {
+            yAxes: [{
+                id: 'first-y-axis',
+                type: 'linear'
+            }, {
+                id: 'second-y-axis',
+                type: 'linear'
+            }]
+        }
+    }
+});
+```
+
+## Creating Multiple Axes
+
+With cartesian axes, it is possible to create multiple X and Y axes. To do so, you can add multiple configuration objects to the `xAxes` and `yAxes` properties. When adding new axes, it is important to ensure that you specify the type of the new axes as default types are **not** used in this case.
+
+In the example below, we are creating two Y axes. We then use the `yAxisID` property to map the datasets to their correct axes.
+
+```javascript
+var myChart = new Chart(ctx, {
+    type: 'line',
+    data: {
+        datasets: [{
+            data: [20, 50, 100, 75, 25, 0],
+            label: 'Left dataset',
+
+            // This binds the dataset to the left y axis
+            yAxisID: 'left-y-axis'
+        }, {
+            data: [0.1, 0.5, 1.0, 2.0, 1.5, 0],
+            label: 'Right dataset',
+
+            // This binds the dataset to the right y axis
+            yAxisID: 'right-y-axis'
+        }],
+        labels: ['Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun']
+    },
+    options: {
+        scales: {
+            yAxes: [{
+                id: 'left-y-axis',
+                type: 'linear',
+                position: 'left'
+            }, {
+                id: 'right-y-axis',
+                type: 'linear',
+                position: 'right'
+            }]
+        }
+    }
+});
+```