plotnine.scale_fill_continuous

scale_fill_continuous(
    cmap_name="viridis",
    *,
    name=None,
    breaks=True,
    limits=None,
    labels=True,
    expand=None,
    guide="colorbar",
    na_value="#7F7F7F",
    aesthetics=(),
    rescaler=rescale,
    oob=censor,
    minor_breaks=True,
    trans=None
)

alias of scale_fill_cmap

Init Parameters

cmap_name: str = 'viridis'

A standard Matplotlib colormap name. The default is viridis. For the list of names checkout the output of matplotlib.cm.cmap_d.keys() or see colormaps.

Parameter Attributes

name: str | None = None

The name of the scale. It is used as the label of the axis or the title of the guide. Suitable defaults are chosen depending on the type of scale.

breaks: ContinuousBreaksUser = True

Major breaks

limits: ContinuousLimitsUser = None

Limits of the scale. Most commonly, these are the minimum & maximum values for the scale. If not specified they are derived from the data. It may also be a function that takes the derived limits and transforms them into the final limits.

labels: ScaleLabelsUser = True

Labels at the breaks. Alternatively, a callable that takes an array_like of break points as input and returns a list of strings.

expand: (
    tuple[float, float]
    | tuple[float, float, float, float]
    | None
) = None

Multiplicative and additive expansion constants that determine how the scale is expanded. If specified must be of length 2 or 4. Specifically the values are in this order:

(mul, add)
(mul_low, add_low, mul_high, add_high)

For example,

  • (0, 0) - Do not expand.
  • (0, 1) - Expand lower and upper limits by 1 unit.
  • (1, 0) - Expand lower and upper limits by 100%.
  • (0, 0, 0, 0) - Do not expand, as (0, 0).
  • (0, 0, 0, 1) - Expand upper limit by 1 unit.
  • (0, 1, 0.1, 0) - Expand lower limit by 1 unit and upper limit by 10%.
  • (0, 0, 0.1, 2) - Expand upper limit by 10% plus 2 units.

If not specified, suitable defaults are chosen.

guide: Literal["legend", "colorbar"] | None = "colorbar"
na_value: str = "#7F7F7F"

Color of missing values.

aesthetics: Sequence[ScaledAestheticsName] = ()

Aesthetics affected by this scale. These are defined by each scale and the user should probably not change them. Have fun.

rescaler: PRescale = rescale

Function to rescale data points so that they can be handled by the palette. Default is to rescale them onto the [0, 1] range. Scales that inherit from this class may have another default.

oob: PCensor = censor

Function to deal with out of bounds (limits) data points. Default is to turn them into np.nan, which then get dropped.

minor_breaks: MinorBreaksUser = True

If a list-like, it is the minor breaks points. If an integer, it is the number of minor breaks between any set of major breaks. If a function, it should have the signature func(limits) and return a list-like of consisting of the minor break points. If None, no minor breaks are calculated. The default is to automatically calculate them.

trans: TransUser = None

The transformation of the scale. Either name of a trans function or a trans function. See mizani.transforms for possible options.

Examples

from plotnine import (
    ggplot,
    aes,
    theme_matplotlib,
    theme_set,
    geom_tile,
    scale_fill_continuous,
    coord_cartesian
)

from plotnine.data import faithfuld

# Set default theme for all the plots
theme_set(theme_matplotlib())

Simple heatmap

Map data to color gradient

Without specifically calling scale_fill_continuous(), a default scale is applied to geom_tile().

faithfuld.head()
eruptions waiting density
0 1.600000 43.0 0.003216
1 1.647297 43.0 0.003835
2 1.694595 43.0 0.004436
3 1.741892 43.0 0.004978
4 1.789189 43.0 0.005424
(
    ggplot(faithfuld, aes("waiting", "eruptions", fill="density")) 
    + geom_tile()
)

Notice that adding scale_fill_continuous() will not change the default plot.

(
    ggplot(faithfuld, aes("waiting", "eruptions", fill="density"))
    + geom_tile()
    + scale_fill_continuous()
)

The scale aesthetics can be edited to other color maps. Use the cmap_name argument to specify an alternative palette. Find other available color maps in the matplotlib documentation.

# Gallery, tiles

(
    ggplot(faithfuld, aes("waiting", "eruptions", fill="density"))
    + geom_tile()
    + scale_fill_continuous(cmap_name="plasma")
    + coord_cartesian(expand=False)
)

Source: Set default theme for all the plots