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Version: Python

Create XY series plots

This guide shows you how to use the plot_xy method to create XY series plots.

XY series plots are generally used to show values over a continuum, such as time. They can be represented as a line, a bar, an area, or a collection of points. The X axis shows the domain, while the Y axis shows the related values at specific points in the range.

Data sourcing​

XY Series plots can be created using data from Deephaven tables, arrays and functions.

From a table​

When data is sourced from a Deephaven table, the following syntax can be used to create an XY series plot:

.plot_xy("series_name", t, "x", "y").show()

  • plot_xy is the method used to create an XY series plot.
  • "series_name" is the name (as a string) you want to use to identify the series on the plot itself.
  • t is the table that holds the data you want to plot.
  • "x" is the name of the column of data to be used for the X value.
  • "y" is the name of the column of data to be used for the Y value.
  • show tells Deephaven to draw the plot in the console.

The example query below will create an XY series plot showing Bitcoin's high on September 8, 2021.

from deephaven import read_csv
from deephaven.plot.figure import Figure

# source the data
source = read_csv(
    "https://media.githubusercontent.com/media/deephaven/examples/main/MetricCentury/csv/metriccentury.csv"
)

# plot the data
plot_single = (
    Figure()
    .plot_xy(
        series_name="Distance",
        t=source.where(filters=["SpeedKPH > 0"]),
        x="Time",
        y="DistanceMeters",
    )
    .show()
)

Plot by some key​

You may want to create a plot with multiple series grouped by a particular key. This can be accomplished using the by parameter.

An individual XY series is plotted for each unique group in the identifier columns.

from deephaven.plot.figure import Figure
from deephaven import empty_table

multi_source = empty_table(20).update(
    ["Letter = (i % 2 == 0) ? `A` : `B`", "X = 0.1 * i", "Y = randomDouble(0.0, 5.0)"]
)

plot_multi = (
    Figure()
    .plot_xy(series_name="Random numbers", t=multi_source, x="X", y="Y", by=["Letter"])
    .show()
)

Shared axes​

You can compare multiple series over the same period of time by creating an XY series plot with shared axes. In the following example, two series are plotted, thereby creating two line graphs on the same plot.

# plot the data
plot_shared_axis = (
    Figure()
    .plot_xy(series_name="Altitude", t=source, x="Time", y="AltitudeMeters")
    .plot_xy(series_name="Speed", t=source, x="Time", y="SpeedKPH")
    .show()
)
tip

You can choose to hide one or more series in the plot. Simply click the series name at the right of the plot to hide it; click the name again to restore it.

Subsequent series can be added to the plot by adding additional plot_xy methods to the query.

Multiple X or Y Axes​

When plotting multiple series in a single plot, the range of the Y axis is an important factor to watch. As the Y axis range increases, value changes become harder to assess.

When the scale of the Y axis needs to cover an extremely wide range, the plot may result in relatively flat lines with barely distinguishable differences in values or trend.

This issue can be easily remedied by adding a second Y axis to the plot via the x_twin method.

x_twin​

The x_twin method enables you to use one Y axis for some of the series being plotted and a second Y axis for the others, while sharing the same X axis:

PlotName = Figure().plot_xy(...).x_twin().plot_xy(...).show()

  • The plot(s) for the series placed before the x_twin() method share a common Y axis (on the left).
  • The plot(s) for the series listed after the x_twin() method share a common Y axis (on the right).
  • All plots share the same X axis.
plot_shared_twin_x = (
    Figure()
    .plot_xy(series_name="Altitude", t=source, x="Time", y="AltitudeMeters")
    .x_twin()
    .plot_xy(series_name="Speed", t=source, x="Time", y="SpeedKPH")
    .show()
)

The value range for the high value is shown on the left axis and the value range for the low value is shown on the right axis.

y_twin​

The y_twin method enables you to use one X axis for one set of the values being plotted and a second X axis for another, while sharing the same Y axis:

plot_name = Figure().plot_xy(...).y_twin().plot_xy(...).show()

  • The plot(s) for the series placed before the y_twin() method use the lower X axis.
  • The plot(s) for the series listed after the y_twin() method use the upper X axis.

Plot colors​

It's easy to change the colors of the lines in an XY series plot using the line method. This example modifies the plot above to have red and yellow lines:

plot_shared_twin_x_colors = (
    Figure()
    .plot_xy(series_name="Altitude", t=source, x="Time", y="AltitudeMeters")
    .line(color="RED")
    .x_twin()
    .plot_xy(series_name="Speed", t=source, x="Time", y="SpeedKPH")
    .line(color="YELLOW")
    .show()
)

You can find the full list of available colors here.

Plot styles​

The XY series plot in Deephaven defaults to a line plot. However, Deephaven's plot_style method can be used to format XY series plots as area charts, stacked area charts, bar charts, stacked bar charts, scatter charts and step charts.

In any of the examples below, you can simply swap out the plot_style argument with the appropriate name; e.g., ("AREA"), ("STACKED_BAR"), ("LINE"), etc.

XY Series as a stacked area plot​

In any of the examples below, you can simply swap out the plot_style argument with the name ("BAR"), ("STACKED_BAR"), ("LINE"), ("AREA"), ("STACKED_AREA"), ("ERROR_BAR"), etc.

from deephaven.plot import PlotStyle

plot_single_stacked_area = (
    Figure()
    .axes(plot_style=PlotStyle.STACKED_AREA)
    .plot_xy(series_name="Heart_rate", t=source, x="Time", y="HeartRate")
    .show()
)

XY Series as a scatter plot​

In the example below, a scatter plot style is used. Additionally, x_twin has been specified to for both plots to share the same X axis.

from deephaven.plot.figure import Figure
from deephaven.plot import PlotStyle
from deephaven.plot import Color, Colors
from deephaven.plot import font_family_names, Font, FontStyle, Shape

plot_xy_scatter = (
    Figure()
    .plot_xy(series_name="Speed", t=source, x="Time", y="SpeedKPH")
    .axes(plot_style=PlotStyle.SCATTER)
    .x_twin()
    .plot_xy(series_name="Distance", t=source, x="Time", y="DistanceMeters")
    .axes(plot_style=PlotStyle.SCATTER)
    .show()
)

XY Series as a scatter plot with markers​

In the example below, the scatter plot includes markers. First, twin method is used to clone the x- and y-axes. Then, the SCATTER PlotStyle is applied to the new axes. The points method draws the plot markers.

from deephaven import time_table
from deephaven.plot.figure import Figure
from deephaven.plot import PlotStyle
from deephaven.plot import Color, Colors
from deephaven.plot import font_family_names, Font, FontStyle, Shape

data = time_table("PT00:00:01").update(
    [
        "Open = 10*sin(0.2*ii) + 2*random()",
        "High = Open + 1",
        "Low = Open - 1",
        "Close = Open + 0.5",
    ]
)

points = data.where("i%5 = 0").view(
    ["Timestamp", "Type= i%3==0 ? `Sell` : `Buy`", "Point = i%3==0 ? High+1 : Low-1"]
)

plot = (
    Figure()
    .figure_title("OHLC + Points")
    .plot_xy(
        series_name="OHLC", t=data, x="Timestamp", y_high="High", y_low="Low", y="Close"
    )
    .twin()
    .axes(plot_style=PlotStyle.SCATTER)
    .plot_xy(series_name="Buy", t=points.where("Type=`Buy`"), x="Timestamp", y="Point")
    .plot_xy(
        series_name="Sell", t=points.where("Type=`Sell`"), x="Timestamp", y="Point"
    )
    .show()
)

XY Series as a step plot​

In the example below, the .plot_style argument has the name ("STEP"). Other parameters are defined to show the fine tuning detail under control.

from deephaven.plot import LineEndStyle, LineJoinStyle, LineStyle

plot_step = (
    Figure()
    .axes(plot_style=PlotStyle.STEP)
    .plot_xy(series_name="HeartRate", t=source, x="Time", y="HeartRate")
    .line(style=LineStyle(width=1.0, end_style=LineEndStyle.ROUND))
    .show()
)

Plot multiple series in a loop​

It's common in data analysis to have multiple series that share an X-axis. In such a case, a for loop can make things easier for plotting. The following example plots three different series on the same plot in a for loop.

from deephaven.plot.figure import Figure
from deephaven import empty_table

source = empty_table(10).update(
    ["X = i", "Y1 = randomInt(1, 10)", "Y2 = randomInt(3, 11)", "Y3 = randomInt(5, 15)"]
)

fig = Figure()

for idx in range(1, 4):
    fig = fig.plot_xy(series_name=f"Y{idx}", t=source, x="X", y=f"Y{idx}")

plot = fig.show()