Reusable contour styles

Instead of repeating styling arguments on every contour() call you can encapsulate them in an ekp.styles.Contour object and reuse it across different maps and domains.

import earthkit.data as ekd

import earthkit.plots as ekp

data = ekd.from_source("sample", "era5-2t-msl-1985122512.grib").to_fieldlist()
pressure = data.sel({"parameter.variable": "msl"})
temperature = data.sel({"parameter.variable": "2t"})

Creating a Contour style

ekp.styles.Contour accepts the same arguments as Map.contour – units, levels, colors, linewidths, linestyles and labels.

msl_style = ekp.styles.Contour(
    units="hPa",
    levels={"step": 4, "reference": 1000},
    colors="plasma",
    linewidths=1,
    labels=True,
)

Pass the style object to Map.contour via the style argument:

chart = ekp.Map(domain="Europe")
chart.contour(pressure, style=msl_style)
chart.legend()
chart.land()
chart.coastlines()
chart.title()
chart.show()

Reusing the style on a different domain

Because the style is a plain Python object you can apply it anywhere:

chart = ekp.Map(domain="North Atlantic")
chart.contour(pressure, style=msl_style)
chart.legend()
chart.land()
chart.coastlines()
chart.title()
chart.show()

Using a colour map vs a single colour

Pass a named matplotlib colour map to colors to tint each line by its value. Pass a plain colour name for uniform lines.

# Colour-mapped version
turbo_style = ekp.styles.Contour(
    units="hPa",
    levels={"step": 4, "reference": 1000},
    colors="turbo",
    linewidths=1,
    labels=True,
)

chart = ekp.Map(domain="Europe")
chart.contour(pressure, style=turbo_style)
chart.legend()
chart.land()
chart.coastlines()
chart.title()
chart.show()

Combining two styles on one map

Define styles for both variables and layer them:

t2m_style = ekp.styles.Style(
    units="celsius",
    colors="RdYlBu_r",
    levels={"step": 4, "reference": 0},
)

msl_bw = ekp.styles.Contour(
    units="hPa",
    levels={"step": 4, "reference": 1000},
    colors="black",
    linewidths=[0.6, 0.6, 0.6, 0.6, 1.4],
    linestyles=["solid", "solid", "solid", "solid", "solid"],
    labels=True,
)

chart = ekp.Map(domain="Europe")
chart.contourf(temperature, style=t2m_style)
chart.contour(pressure, style=msl_bw)
chart.legend()
chart.land()
chart.borders()
chart.coastlines()
chart.title()
chart.show()