# Cartesian Coordinates¶

In Toyplot,
`cartesian coordinates`

provide
a traditional mapping of two-dimensional data values on the plane to
canvas coordinates. The axes *range* (the area on the canvas that they
occupy) is specified when they are created (see Canvas Layout).
Their *domain* is implicitly defined to include all of the data in the
plot (but can be manually overridden by the caller if desired).

If your data is one-dimensional, you should consider using Numberline Coordinates instead.

Cartesian coordinates are either created for you implicitly when using the Convenience API:

```
import numpy
y = numpy.linspace(0, 1, 20) ** 2
```

```
import toyplot
canvas, axes, mark = toyplot.plot(y, width=300)
```

... or explicitly using `toyplot.canvas.Canvas.cartesian()`

:

```
canvas = toyplot.Canvas(width=300)
axes = canvas.cartesian()
axes.plot(y);
```

## Properties¶

Axes objects contain sets of nested properties that can be used to adjust behavior. The list of available properties includes the following:

- axes.show - set to
*False*to hide the axes completely (the plotted data will still be visible). - axes.aspect - set to “fit-range” to alter the domain so that its aspect ratio matches the aspect ratio of the range.
- axes.padding - a small gap between the axes and their contents. Defaults to CSS pixels, supports all Units.
- axes.label.text - optional label at the top of the axes.
- axes.label.style - styles the axes label text.
- axes.coordinates.show - set to
*False*to disable interactive mouse coordinates. - axes.coordinates.style - styles the interactive mouse coordinates background.
- axes.coordinates.label.style - styles the interactive mouse coordinates text.
- axes.x.show - set to
*False*to hide the X axis completely. - axes.x.scale - “linear”, “log” (base 10), “log10”, “log2”, or a (“log”, base) tuple. See Logarithmic Scales for details.
- axes.x.domain.min - override the minimum domain value for the axis.
- axes.x.domain.max - override the maximum domain value for the axis.
- axes.x.label.location - “above” or “below”, to specify on which side of the axis the label is placed.
- axes.x.label.offset - offsets the label from the axis. Defaults to CSS pixels, supports all Units.
- axes.x.label.text - optional label below the X axis.
- axes.x.label.style - styles the X axis label.
- axes.x.spine.show - set to
*False*to hide the X axis spine. - axes.x.spine.position - set to “low”, “high”, or a Y axis domain value to position the spine. Defaults to “low”.
- axes.x.spine.style - styles the X axis spine.
- axes.x.ticks.show - set to
*True*to display X axis tick marks. - axes.x.ticks.locator - assign an instance of
`toyplot.locator.TickLocator`

to control the positioning and formatting of ticks and tick labels. By default, an appropriate locator is automatically chosen based on the axis scale and domain. See Tick Locators for details. - axes.x.ticks.location - “above” or “below”, to specify on which side of the axis the ticks and labels are placed.
- axes.x.ticks.near - length of X axis ticks on the same side of the axis as the tick labels. Defaults to CSS pixels, supports all Units.
- axes.x.ticks.far - length of X axis ticks on the opposite side of the axis as the tick labels. Defaults to CSS pixels, supports all Units.
- axes.x.ticks.style - styles the X axis ticks.
- axes.x.ticks.labels.angle - set the angle of X axis tick labels in degrees.
- axes.x.ticks.labels.offset - offsets labels from the axis. Defaults to CSS pixels, supports all Units.
- axes.x.ticks.labels.show - set to
*False*to hide X axis tick labels. - axes.x.ticks.labels.style - style X axis tick label text.
- ... and equivalent properties for the Y axis.

In the following example we override several of the defaults:

```
x = numpy.linspace(0, 2 * numpy.pi)
y = numpy.sin(x)
```

```
import toyplot.locator
canvas = toyplot.Canvas(width=600, height=300)
axes = canvas.cartesian()
axes.label.text = "Trigonometry 101"
axes.x.label.text = "x"
axes.y.label.text = "sin(x)"
axes.x.ticks.show = True
axes.x.ticks.locator = toyplot.locator.Explicit(
[0, numpy.pi / 2, numpy.pi, 3 * numpy.pi / 2, 2 * numpy.pi],
["0", u"\u03c0 / 2", u"\u03c0", u"3 \u03c0 / 2", u"2 \u03c0"])
mark = axes.plot(x, y)
```

As a convenience, some of the most common properties can also be set when the axes are created:

```
x = numpy.linspace(0, 10, 100)
y = 40 + x ** 2
```

```
canvas = toyplot.Canvas(300, 300)
axes = canvas.cartesian(label="Toyplot Users", xlabel="Days", ylabel="Users")
mark = axes.plot(x, y)
```

And the same properties can be used with the Convenience API, as in the following example where we specify a minimum value for an axis - for example, if we wanted the previous figure to include \(y = 0\):

```
toyplot.plot(
x,
y,
label="Toyplot Users",
xlabel="Days",
ylabel="Users",
ymin=0,
width=300);
```