Plots’ operations

Merging plots

CasysPlot can be merged together in order to display them on the same plot. This merge operation is done using the add_plot() method.

Add a plot to the current one.

The provided plot is copied with its current parameters. Modifying it afterward
won't affect the added plot, you have to set it before.

Parameters
----------
cplot
    CasysPlot to add.
shared_ax
    Axis to share with the current plot (x, y or all).

from casys import CasysPlot

plot_1 = CasysPlot(
    data=ad,
    data_name='Ku-band range std fct swh',
    stat="mean",
)

plot_2 = CasysPlot(
    data=ad,
    data_name='C-band range std fct swh',
    stat="mean"
)

plot_1.add_plot(plot_2, shared_ax="all")
plot_1.show()

Warning

Only CasysPlot of the same family can be merged together (i.e. you cannot merge a geographical box map with an along time curve).

For a additional examples on how to merge plots, visit this notebook.

Concatenating plots’ data

Sometime you might end up with CasysPlot representing the same data for different periods. All of these plots’ data can be concatenated into one with the concatenate_data() method.

Concatenate data from provided plots into the current one.

Parameters
----------
cplots
    List of plots to concatenate.

Warning

Trying to concatenate plots containing different data might lead to unexpected things.

Plots’ arithmetic

Operations on CasysPlot objects can be made without having to access their data attribute.

These operations are applied to the underlying xarray Dataset or DataArray containing the plot’s data.

Example: Manually computing a ratio.

from casys import CasysPlot

plot_1 = CasysPlot(
    data=ad,
    data_name="Rejected data, mean by pass",
    stat="count"
)

plot_2 = CasysPlot(
    data=ad,
    data_name="Number of points, mean by pass",
    stat="count"
)

plot_ratio = (plot_1 / plot_2) * 100
plot_ratio.set_title("Percentage of rejected points")
plot_ratio.set_ylabel("Rejected points (%)")

plot_ratio.show()

Example: A complex calculation that have no scientific meaning but might give you some ideas.

from casys import CasysPlot

# Temporal plots definitions:
sla_mean = CasysPlot(
    data=ad,
    data_name="SLA (6h)",
    stat="mean"
)
sla_std = CasysPlot(
    data=ad,
    data_name="SLA (6h)",
    stat="std"
)
sig_mean = CasysPlot(
    data=ad,
    data_name="SIG0 (6h)",
    stat="mean"
)
sig_count = CasysPlot(
    data=ad,
    data_name="SIG0 (6h)",
    stat="count"
)

# Along track data plots definitions:
cp1 = CasysPlot(data=ad, data_name="SLA")
cp2 = CasysPlot(data=ad, data_name="Wind speed")

# Calculations:
cp_x = (sla_mean + (0.1 * sig_count)) / (sla_std * sig_mean)
cp_x.show()

lat = cp1.data["LATITUDE"]

coef_wind = (cp2 / 23.28)
coef_lat = abs(lat / 190)

cp_coef = cp1 * coef_wind * coef_lat
cp_coef.show()

These operations are implemented using Python operator methods.

Available operations are:

Unary operators:

neg

abs

pos

invert

Binary operator:

add

sub

mul

truediv

floordiv

mod

pow

Raw data coordinates adjustment

When working with raw data map plots you might be interested in showing two fields’ values of a same pass.

In order for them to not overlap you can use the adjust_coordinates() method allowing to adjust longitudes and/or latitudes of a plot by a given value.

Adjust plots longitudes and latitudes coordinates.

Parameters
----------
longitude
    Value to add.
latitude
    Value to add.

from casys import AxeParams, CasysPlot, DataParams, DateHandler, PlotParams

pass_77 = (
    DateHandler.from_orf("C_J3_GDRD", 122, 77, pos="first"),
    DateHandler.from_orf("C_J3_GDRD", 122, 77, pos="last"),
)

sig0_plot_par = PlotParams(
    fig_width=5.5,
    fig_height=8,
    x_limits=(80, 110),
    y_limits=(-50, 20),
    color_limits=(0, 17),
    color_map="autumn",
    color_bar=AxeParams(position="right"),
)

sig0_77_plot = CasysPlot(
    data=ad,
    data_name="Sigma 0",
    plot="map",
    plot_params=sig0_plot_par,
    data_params=DataParams(time_limits=pass_77),
)


sla_plot_par = PlotParams(color_limits=(-4, -1), color_bar=AxeParams(position="right"))

sla_77_plot = CasysPlot(
    data=ad,
    data_name="SLA",
    plot="map",
    plot_params=sla_plot_par,
    data_params=DataParams(time_limits=pass_77),
)

# Adjusting sla plot longitudes so they do not overlap each other.
sla_77_plot.adjust_coordinates(longitude=1)

# Adding statistics
sla_77_plot.add_stat_bar()
sig0_77_plot.add_stat_bar()

# Merging plots
sig0_77_plot.add_plot(sla_77_plot)

sig0_77_plot.show()

This example along with some others might be found in the following notebook.