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Axes in Julia

How to adjust axes properties in Julia - axes titles, styling and coloring axes and grid lines, ticks, tick labels and more.


This tutorial explain how to set the properties of [2-dimensional Cartesian axes], namely layout.xaxis and layout.yaxis.

Other kinds of subplots and axes are described in other tutorials:

See also the tutorials on subplots and multiple axes.

2-D Cartesian Axis Types and Auto-Detection

The different types of Cartesian axes are configured via the xaxis.type or yaxis.type attribute, which can take on the following values:

The axis type is auto-detected by looking at data from the first [trace] linked to this axis:

  • First check for multicategory, then date, then category, else default to linear (log is never automatically selected)

  • multicategory is just a shape test: is the array nested?

  • date and category: require more than twice as many distinct date or category strings as distinct numbers in order to choose that axis type.

    • Both of these test an evenly-spaced sample of at most 1000 values

Forcing an axis to be categorical

It is possible to force the axis type by setting explicitly xaxis_type. In the example below the automatic X axis type would be linear (because there are not more than twice as many unique strings as unique numbers) but we force it to be category.

using PlotlyJS

trace = bar(x=["a", "a", "b", 3], y = [1,2,3,4])
layout = Layout(xaxis_type="category")

plot(trace, layout)

General Axis properties

The different groups of Cartesian axes properties are

  • title of the axis

  • tick values (locations of tick marks) and tick labels. Tick labels and grid lines are placed at tick values.

  • lines: grid lines (passing through tick values), axis lines, zero lines

  • range of the axis

  • domain of the axis

The examples on this page apply to axes of any type, but extra attributes are available for axes of type category and axes of type date.

Set and Style Axes Title Labels

Set axis title text

Axis titles are automatically set to the column names when using plot and using DataFrame as input.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "tips")
plot(df, x=:total_bill, y=:tip, color=:sex, mode="markers", type="scatter")

Axis titles can also be overridden using the [axis]_title argument of Layout:

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "tips")
layout = Layout(
    xaxis_title="Total Bill(\$)",
    yaxis_title="Tip (\$)",
    legend_title_text="Legend"
)
trace = scatter(df, x=:total_bill, y=:tip, color=:sex, mode="markers",)

plot(trace, layout)

Moving Tick Labels Inside the Plot

The ticklabelposition attribute moves tick labels inside the plotting area, and modifies the auto-range behaviour to accommodate the labels.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "stocks")
layout = Layout(ticklabelposition="inside top", title=missing)
trace = bar(df, x=:date, y=(df.GOOG .- 1))

plot(trace, layout)
Set axis title text with Graph Objects

Axis titles are set using the nested title property of the x or y axis. Here is an example of creating a new figure and using Layout, with magic underscore notation, to set the axis titles.

using PlotlyJS

trace = scatter(y=[1, 0], x=[0,1])

layout = Layout(xaxis_title="Time", yaxis_title="Value A")

plot(trace, layout)

Set axis title position

This example sets standoff attribute to cartesian axes to determine the distance between the tick labels and the axis title. Note that the axis title position is always constrained within the margins, so the actual standoff distance is always less than the set or default value. By default automargin is True in Plotly template for the cartesian axis, so the margins will be pushed to fit the axis title at given standoff distance.

using PlotlyJS

trace = scatter(
    mode = "lines+markers",
    y=[4, 1, 3],
    x=["December", "January", "February"]
)

layout = Layout(
    xaxis=attr(
        tickangle=90,
        title_text = "Month",
        title_font_size=20,
        title_standoff=25
    ),
    yaxis=attr(
        title_text = "Temperature",
        title_standoff=25
    )
)

plot(trace, layout)
Set axis title font

Here is an example that configures the font family, size, and color for the axis titles in a figure.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")


plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    mode="markers", kind="scatter",
    Layout(
       xaxis=attr(
            title_text="sepal_width",
            title_font=attr(size=18, family="Courier", color="crimson")
        ),
        yaxis=attr(
            title_text="sepal_length",
            title_font=attr(size=18, family="Courier", color="crimson")
        )
    )
)

Tick Placement, Color, and Style

Set number of tick marks (and grid lines)

The approximate number of ticks displayed for an axis can be specified using the nticks axis property.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    Layout(yaxis=attr(tickmode="auto",nticks=20)),
    kind="scatter", mode="markers"
)
Set start position and distance between ticks

The tick0 and dtick axis properties can be used to control to placement of axis ticks as follows: If specified, a tick will fall exactly on the location of tick0 and additional ticks will be added in both directions at intervals of dtick.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(yaxis=attr(dtick=0.5, tick0=0.25)),
)
Set exact location of axis ticks

It is possible to configure an axis to display ticks at a set of predefined locations by setting the tickvals property to an array of positions.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(yaxis_tickvals=[5.1, 5.9, 6.3, 7.5]),
)
Style tick marks

The ticks axis property controls how the tick marks are draw. Set ticks to "inside" (to place ticks inside plotting area or "outside" to place ticks outside the plotting area.

The appearance of these tick marks can be customized by setting their length (ticklen), width (tickwidth), and color (tickcolor).

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(
        yaxis=attr(ticks="outside", tickwidth=2, tickcolor="crimson", ticklen=10, col=1),
        xaxis=attr(ticks="outside", tickwidth=2, tickcolor="crimson", ticklen=10)
    ),
)
Toggling axis labels

The axis tick mark labels can be disabled by setting the showticklabels axis property to false.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(
        yaxis=attr(showticklabels=false),
        xaxis=attr(showticklabels=false)
    ),
)
Set axis label rotation and font

The orientation of the axis tick mark labels is configured using the tickangle axis property. The value of tickangle is the angle of rotation, in the clockwise direction, of the labels from vertical in units of degrees. The font family, size, and color for the tick labels are stored under the tickfont axis property.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "tips")
plot(
    df, x=:sex, y=:tip,  facet_col=:smoker,
    type="histogram", histfunc="sum",
    Layout(
       xaxis=attr(tickangle=45, tickfont=attr(family="Rockwell", color="crimson", size=14))
    )
)

Enumerated Ticks with Tickvals and Ticktext

The tickvals and ticktext axis properties can be used together to display custom tick label text at custom locations along an axis. They should be set to lists of the same length where the tickvals list contains positions along the axis, and ticktext contains the strings that should be displayed at the corresponding positions.

Here is an example.

using PlotlyJS, CSV, HTTP, Dates

# Load and filter Apple stock data for 2016
apple_df = CSV.File(
    HTTP.get("https://raw.githubusercontent.com/plotly/datasets/master/finance-charts-apple.csv").body
) |> DataFrame

apple_df_2016 = apple_df[year.(apple_df.Date) .== 2016, :]

layout = Layout(
    # Set custom x-axis labels
    xaxis=attr(
        tickmode="array",
        ticktext=["End of Q1", "End of Q2", "End of Q3", "End of Q4"],
        tickvals=[Date("2016-04-01"), Date("2016-07-01"), Date("2016-10-01"), maximum(apple_df_2016.Date)],
    ),
    # Prefix y-axis tick labels with dollar sign
    yaxis_tickprefix="\$",
    # Set figure title
    title_text = "Apple Stock Price"
)
# Create figure and add line
plot(
    apple_df_2016, x=:Date, y=Symbol("AAPL.High"),
    kind="scatter", mode="lines",
    layout
)

Axis lines: grid and zerolines

Toggling Axis grid lines

Axis grid lines can be disabled by setting the showgrid property to False for the x and/or y axis.

Here is an example of setting showgrid to False in the graph object figure constructor.

using PlotlyJS

plot(
    scatter(mode="lines", y=[1, 0], x=[0,1]),
    Layout(xaxis_showgrid=false, yaxis_showgrid=false)
)
Toggling Axis zero lines

The lines passing through zero can be disabled as well by setting the zeroline axis property to False

using PlotlyJS

plot(scatter(mode="lines", y=[1, 0], x=[0,1]),
    Layout(
        xaxis_showgrid=false,
        xaxis_zeroline=false,
        yaxis_showgrid=false,
        yaxis_zeroline=false
    )
)

Styling and Coloring Axes and the Zero-Line

Styling axis lines

The showline axis property controls the visibility of the axis line, and the linecolor and linewidth axis properties control the color and width of the axis line.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "tips")

plot(
    df, x=:sex, y=:tip, facet_col=:smoker,
    kind="histogram",  histfunc="sum",
    Layout(
        yaxis=attr(showline=true, linewidth=2, linecolor="black"),
        xaxis=attr(showline=true, linewidth=2, linecolor="black")
    )
)
Mirroring axis lines

Axis lines can be mirrored to the opposite side of the plotting area by setting the mirror axis property to true.

using PlotlyJS, CSV, DataFrames

df = dataset(DataFrame, "tips")

plot(
    df, x=:sex, y=:tip, facet_col=:smoker,
    kind="histogram",  histfunc="sum",
    Layout(
        yaxis=attr(showline=true, linewidth=2, linecolor="black", mirror=true),
        xaxis=attr(showline=true, linewidth=2, linecolor="black", mirror=true)
    )
)
Styling grid lines

The width and color of axis grid lines are controlled by the gridwidth and gridcolor axis properties.

using PlotlyJS, CSV, DataFrames
df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(
        yaxis=attr(showgrid=true, gridwidth=1, gridcolor="LightPink"),
        xaxis=attr(showgrid=true, gridwidth=1, gridcolor="LightPink")
    ),
)
Styling zero lines

The width and color of axis zero lines are controlled by the zerolinewidth and zerolinecolor axis properties.

Here is an example of configuring the zero line width and color for a simple figure using the update_xaxes and update_yaxes graph object figure methods.

using PlotlyJS

plot(scatter(y=[1, 0], x=[0,1]), Layout(
    xaxis=attr(zeroline=true, zerolinewidth=2, zerolinecolor="LightPink"),
    yaxis=attr(zeroline=true, zerolinewidth=2, zerolinecolor="LightPink")
))

Setting the Range of Axes Manually

The visible x and y axis range can be configured manually by setting the range axis property to a list of two values, the lower and upper boundary.

using PlotlyJS, CSV, DataFrames
df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(xaxis_range=[1.5, 4.5], yaxis_range=[3, 9]),
)

Disabling Pan/Zoom on Axes (Fixed Range)

Pan/Zoom can be disabled for a given axis by setting fixedrange to True.

using PlotlyJS, CSV, DataFrames
df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(xaxis=attr(fixedrange=true),),
)

Fixed Ratio Axes

The scaleanchor and scaleratio axis properties can be used to force a fixed ratio of pixels per unit between two axes.

Here is an example of anchoring the scale of the x and y axis with a scale ratio of 1. Notice how the zoom box is constrained to prevent the distortion of the shape of the line plot.

using PlotlyJS

layout = Layout(
    width=800,
    height=500,
    title="fixed-ratio axes",
    yaxis=attr(scaleanchor="x", scaleratio=1)
)
trace = scatter(
    x=[0,1,1,0,0,1,1,2,2,3,3,2,2,3],
    y=[0,0,1,1,3,3,2,2,3,3,1,1,0,0]
)

plot(trace, layout)

Fixed Ratio Axes with Compressed domain

If an axis needs to be compressed (either due to its own scaleanchor and scaleratio or those of the other axis), constrain determines how that happens: by increasing the "range" (default), or by decreasing the "domain".

using PlotlyJS

layout = Layout(
    width=800, height=500,
    title="fixed-ratio axes with compressed axes",
    yaxis=attr( scaleanchor="x", scaleratio=1),
    xaxis=attr(range=[-1,4], constrain="domain")
)

trace = scatter(
    x=[0,1,1,0,0,1,1,2,2,3,3,2,2,3],
    y=[0,0,1,1,3,3,2,2,3,3,1,1,0,0]
)

plot(trace, layout)
Decreasing the domain spanned by an axis

In the example below, the x and y axis are anchored together, and the range of the xaxis is set manually. By default, plotly extends the range of the axis (overriding the range parameter) to fit in the figure domain. You can restrict the domain to force the axis to span only the set range, by setting constrain='domain' as below.

using PlotlyJS

layout = Layout(
    width=800, height=500, title="fixed-ratio axes",
    yaxis=attr(range=(-0.5, 3.5), constrain="domain"),
    xaxis=attr(scaleanchor="x", scaleratio=1)
)

trace = scatter(
    x=[0,1,1,0,0,1,1,2,2,3,3,2,2,3],
    y=[0,0,1,1,3,3,2,2,3,3,1,1,0,0]
)

plot(trace, layout)

Fixed Ratio Axes with Compressed domain

If an axis needs to be compressed (either due to its own scaleanchor and scaleratio or those of the other axis), constrain determines how that happens: by increasing the "range" (default), or by decreasing the "domain".

using PlotlyJS

layout = Layout(
    width=800, height=500, title="fixed-ratio axes",
    yaxis=attr(scaleanchor="x",scaleratio=1),
    xaxis=attr(
        range=[-1,4],  # sets the range of xaxis
        constrain="domain",  # meanwhile compresses the xaxis by decreasing its "domain"
    )
)

trace = scatter(
    x=[0,1,1,0,0,1,1,2,2,3,3,2,2,3],
    y=[0,0,1,1,3,3,2,2,3,3,1,1,0,0]
)

plot(trace, layout)

Reversed Axes

You can tell plotly's automatic axis range calculation logic to reverse the direction of an axis by setting the autorange axis property to "reversed".

using PlotlyJS, CSV, DataFrames
df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(yaxis_autorange="reversed"),
)

Reversed Axes with Range ( Min/Max ) Specified

The direction of an axis can be reversed when manually setting the range extents by specifying a list containing the upper bound followed by the lower bound (rather that the lower followed by the upper) as the range axis property.

using PlotlyJS, CSV, DataFrames
df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(yaxis_range=[9, 3]),
)

Axis range for log axis type

If you are using a log type of axis and you want to set the range of the axis, you have to give the log10 value of the bounds.

using PlotlyJS

x = range(1, stop=200, length=30)
plot(
    scatter(x=x, y=x.^3, range_x=[0.8, 250], mode="markers"),
    Layout(
        yaxis_type="log",
        xaxis_type="log",
        xaxis_range=[log10(0.8), log10(250)]
    )
)

<code>nonnegative</code>, <code>tozero</code>, and <code>normal</code> Rangemode

The axis auto-range calculation logic can be configured using the rangemode axis parameter.

If rangemode is "normal" (the default), the range is computed based on the min and max values of the input data. If "tozero", the range will always include zero. If "nonnegative", the range will not extend below zero, regardless of the input data.

using PlotlyJS

df = dataset(DataFrame, "iris")

plot(
    df, x=:sepal_width, y=:sepal_length, facet_col=:species,
    kind="scatter", mode="markers",
    Layout(yaxis_range=[9, 3]),
)

Setting the domain of the axis

using PlotlyJS


plot(
    scatter(
        x=[0,1,1,0,0,1,1,2,2,3,3,2,2,3],
        y=[0,0,1,1,3,3,2,2,3,3,1,1,0,0]
    ),
    Layout(
        yaxis_domain=(0.25, 0.75),
        xaxis_domain=(0.25,0.75)
    )
)

Reference

See https://plotly.com/julia/reference/layout/xaxis/ and https://plotly.com/julia/reference/layout/yaxis/ for more information and chart attribute options!