1D plotting commands

Proplot adds several new features to matplotlib’s plotting commands using the intermediate PlotAxes class. For the most part, these additions represent a superset of matplotlib – if you are not interested, you can use the plotting commands just like you would in matplotlib. This section documents the features added for 1D plotting commands like plot, scatter, and bar.

Data arguments

The treatment of data arguments passed to the 1D PlotAxes commands is standardized. For each command, you can optionally omit the dependent variable coordinates, in which case they are inferred from the data (see xarray and pandas integration), or pass 2D dependent or independent variable coordinates, in which case the plotting command is called for each column of the 2D array(s). If coordinates are string labels, they are converted to indices and tick labels using IndexLocator and IndexFormatter. If coordinates are descending and the axis limits are unset, the axis direction is automatically reversed. All positional arguments can also be specified as keyword arguments (see the documentation for each plotting command).

Note

By default, when choosing the x or y axis limits, proplot ignores out-of-bounds data along the other axis if it was explicitly fixed by set_xlim or set_ylim (or, equivalently, by passing xlim or ylim to proplot.axes.CartesianAxes.format). This can be useful if you wish to restrict the view along a “dependent” variable axis within a large dataset. To disable this feature, pass inbounds=False to the plotting command or set rc['axes.inbounds'] to False (see also the rc['cmap.inbounds'] setting and the user guide).

import proplot as pplt
import numpy as np

N = 5
state = np.random.RandomState(51423)
with pplt.rc.context({'axes.prop_cycle': pplt.Cycle('Grays', N=N, left=0.3)}):
    # Sample data
    x = np.linspace(-5, 5, N)
    y = state.rand(N, 5)
    fig = pplt.figure(share=False, suptitle='Standardized input demonstration')

    # Plot by passing both x and y coordinates
    ax = fig.subplot(121, title='Manual x coordinates')
    ax.area(x, -1 * y / N, stack=True)
    ax.bar(x, y, linewidth=0, alpha=1, width=0.8)
    ax.plot(x, y + 1, linewidth=2)
    ax.scatter(x, y + 2, marker='s', markersize=5**2)

    # Plot by passing just y coordinates
    # Default x coordinates are inferred from DataFrame,
    # inferred from DataArray, or set to np.arange(0, y.shape[0])
    ax = fig.subplot(122, title='Auto x coordinates')
    ax.area(-1 * y / N, stack=True)
    ax.bar(y, linewidth=0, alpha=1)
    ax.plot(y + 1, linewidth=2)
    ax.scatter(y + 2, marker='s', markersize=5**2)
    fig.format(xlabel='xlabel', ylabel='ylabel')

/home/docs/checkouts/readthedocs.org/user_builds/proplot/conda/latest/lib/python3.8/site-packages/proplot/__init__.py:73: ProplotWarning: Rebuilding font cache. This usually happens after installing or updating proplot.
  register_fonts(default=True)

import proplot as pplt
import numpy as np

# Sample data
cycle = pplt.Cycle('davos', right=0.8)
state = np.random.RandomState(51423)
N, M = 400, 20
xmax = 20
x = np.linspace(0, 100, N)
y = 100 * (state.rand(N, M) - 0.42).cumsum(axis=0)

# Plot the data
fig = pplt.figure(refwidth=2.2, share=False)
axs = fig.subplots([[0, 1, 1, 0], [2, 2, 3, 3]], wratios=(2, 1, 1, 2))
axs[0].axvspan(
    0, xmax, zorder=3, edgecolor='red', facecolor=pplt.set_alpha('red', 0.2),
)
for i, ax in enumerate(axs):
    inbounds = i == 1
    title = f'Restricted xlim inbounds={inbounds}'
    title += ' (default)' if inbounds else ''
    ax.format(
        xmax=(None if i == 0 else xmax),
        title=('Default xlim' if i == 0 else title),
    )
    ax.plot(x, y, cycle=cycle, inbounds=inbounds)
fig.format(
    xlabel='xlabel',
    ylabel='ylabel',
    suptitle='Default ylim restricted to in-bounds data'
)

Pandas and xarray integration

The 1D PlotAxes commands recognize pandas and xarray data structures. If you omit dependent variable coordinates, the commands try to infer them from the pandas.Series, pandas.DataFrame, or xarray.DataArray. If you did not explicitly set the x or y axis label or legend or colorbar label(s), the commands try to retrieve them from the pandas.DataFrame or xarray.DataArray. The commands also recognize pint.Quantity structures and apply unit string labels with formatting specified by rc.unitformat = 'L'.

These features restore some of the convenience you get with the builtin pandas and xarray plotting functions. They are also optional – installation of pandas and xarray are not required to use proplot. The automatic labels can be disabled by setting rc.autoformat to False or by passing autoformat=False to any plotting command.

Note

For every plotting command, you can pass a Dataset, DataFrame, or dict to the data keyword with strings as data arguments instead of arrays – just like matplotlib. For example, ax.plot('y', data=dataset) and ax.plot(y='y', data=dataset) are translated to ax.plot(dataset['y']). This is the preferred input style for most seaborn plotting commands. Also, if you pass a pint.Quantity or DataArray containing a pint.Quantity, proplot will automatically call setup_matplotlib so that the axes become unit-aware.

import xarray as xr
import numpy as np
import pandas as pd

# DataArray
state = np.random.RandomState(51423)
data = (
    np.sin(np.linspace(0, 2 * np.pi, 20))[:, None]
    + state.rand(20, 8).cumsum(axis=1)
)
coords = {
    'x': xr.DataArray(
        np.linspace(0, 1, 20),
        dims=('x',),
        attrs={'long_name': 'distance', 'units': 'km'}
    ),
    'num': xr.DataArray(
        np.arange(0, 80, 10),
        dims=('num',),
        attrs={'long_name': 'parameter'}
    )
}
da = xr.DataArray(
    data, dims=('x', 'num'), coords=coords, name='energy', attrs={'units': 'kJ'}
)

# DataFrame
data = (
    (np.cos(np.linspace(0, 2 * np.pi, 20))**4)[:, None] + state.rand(20, 5) ** 2
)
ts = pd.date_range('1/1/2000', periods=20)
df = pd.DataFrame(data, index=ts, columns=['foo', 'bar', 'baz', 'zap', 'baf'])
df.name = 'data'
df.index.name = 'date'
df.columns.name = 'category'

import proplot as pplt
fig = pplt.figure(share=False, suptitle='Automatic subplot formatting')

# Plot DataArray
cycle = pplt.Cycle('dark blue', space='hpl', N=da.shape[1])
ax = fig.subplot(121)
ax.scatter(da, cycle=cycle, lw=3, colorbar='t', colorbar_kw={'locator': 20})

# Plot Dataframe
cycle = pplt.Cycle('dark green', space='hpl', N=df.shape[1])
ax = fig.subplot(122)
ax.plot(df, cycle=cycle, lw=3, legend='t', legend_kw={'frame': False})

<a list of 5 Line2D objects>

Changing the property cycle

It is often useful to create custom property cycles on-the-fly and use different property cycles for different plot elements. You can do so using the cycle and cycle_kw keywords, available with most 1D PlotAxes commands. cycle and cycle_kw are passed to the Cycle constructor function, and the resulting property cycle is used for the plot. You can specify cycle once with 2D input data (in which case each column is plotted in succession according to the property cycle) or call a plotting command multiple times with the same cycle argument (the property cycle is not reset). You can also disable property cycling with cycle=False, cycle='none', or cycle=() and re-enable the default property cycle with cycle=True (note that as usual, you can also simply override the property cycle with relevant artist keywords like color). For more information on property cycles, see the color cycles section and this matplotlib tutorial.

import proplot as pplt
import numpy as np

# Sample data
M, N = 50, 5
state = np.random.RandomState(51423)
data1 = (state.rand(M, N) - 0.48).cumsum(axis=1).cumsum(axis=0)
data2 = (state.rand(M, N) - 0.48).cumsum(axis=1).cumsum(axis=0) * 1.5
data1 += state.rand(M, N)
data2 += state.rand(M, N)

with pplt.rc.context({'lines.linewidth': 3}):
    # Use property cycle for columns of 2D input data
    fig = pplt.figure(share=False)
    ax = fig.subplot(121, title='Single plot call')
    ax.plot(
        2 * data1 + data2,
        cycle='black',  # cycle from monochromatic colormap
        cycle_kw={'ls': ('-', '--', '-.', ':')}
    )

    # Use property cycle with successive plot() calls
    ax = fig.subplot(122, title='Multiple plot calls')
    for i in range(data1.shape[1]):
        ax.plot(data1[:, i], cycle='Reds', cycle_kw={'N': N, 'left': 0.3})
    for i in range(data1.shape[1]):
        ax.plot(data2[:, i], cycle='Blues', cycle_kw={'N': N, 'left': 0.3})
    fig.format(
        xlabel='xlabel', ylabel='ylabel', suptitle='On-the-fly property cycles'
    )

Line plots

Line plots can be drawn with plot or plotx (or their aliases, line or linex). For the x commands, positional arguments are interpreted as x coordinates or (y, x) pairs. This is analogous to barh and fill_betweenx. Also, the default x bounds for lines drawn with plot and y bounds for lines drawn with plotx are now “sticky”, i.e. there is no padding between the lines and axes edges by default.

Step and stem plots can be drawn with step, stepx, stem, and stemx. Plots of parallel vertical and horizontal lines can be drawn with vlines and hlines. You can have different colors for “negative” and “positive” lines using negpos=True (see below for details).

import proplot as pplt
import numpy as np
state = np.random.RandomState(51423)
gs = pplt.GridSpec(nrows=3, ncols=2)
fig = pplt.figure(refwidth=2.2, span=False, share='labels')

# Vertical vs. horizontal
data = (state.rand(10, 5) - 0.5).cumsum(axis=0)
ax = fig.subplot(gs[0], title='Dependent x-axis')
ax.line(data, lw=2.5, cycle='seaborn')
ax = fig.subplot(gs[1], title='Dependent y-axis')
ax.linex(data, lw=2.5, cycle='seaborn')

# Vertical lines
gray = 'gray7'
data = state.rand(20) - 0.5
ax = fig.subplot(gs[2], title='Vertical lines')
ax.area(data, color=gray, alpha=0.2)
ax.vlines(data, negpos=True, lw=2)

# Horizontal lines
ax = fig.subplot(gs[3], title='Horizontal lines')
ax.areax(data, color=gray, alpha=0.2)
ax.hlines(data, negpos=True, lw=2)

# Step
ax = fig.subplot(gs[4], title='Step plot')
data = state.rand(20, 4).cumsum(axis=1).cumsum(axis=0)
cycle = ('gray6', 'blue7', 'red7', 'gray4')
ax.step(data, cycle=cycle, labels=list('ABCD'), legend='ul', legend_kw={'ncol': 2})

# Stems
ax = fig.subplot(gs[5], title='Stem plot')
data = state.rand(20)
ax.stem(data)
fig.format(suptitle='Line plots demo', xlabel='xlabel', ylabel='ylabel')

Scatter plots

The scatter command now permits omitting x coordinates and accepts 2D y coordinates, just like plot. As with plotx, the scatterx command is just like scatter, except positional arguments are interpreted as x coordinates and (y, x) pairs. scatter also now accepts keywords that look like plot keywords (e.g., color instead of c and markersize instead of s). This way, scatter can be used to simply “plot markers, not lines” without changing the input arguments relative to plot.

The property cycler used by scatter can be changed using the cycle keyword argument, and unlike matplotlib it can include properties like marker and markersize. The colormap cmap and normalizer norm used with the optional c color array are now passed through the Colormap and Norm constructor functions.

Important

In matplotlib, arrays passed to the marker size keyword s always represent the area in units points ** 2. In proplot, arrays passed to s are scaled so that the minimum data value has the area 1 while the maximum data value has the area rc['lines.markersize'] squared. These minimum and maximum marker sizes can also be specified manually with the smin and smax keywords, analogous to vmin and vmax used to scale the color array c. This feature can be disabled by passing absolute_size=True to scatter or scatterx. This is done automatically when seaborn calls scatter internally.

import proplot as pplt
import numpy as np
import pandas as pd

# Sample data
state = np.random.RandomState(51423)
x = (state.rand(20) - 0).cumsum()
data = (state.rand(20, 4) - 0.5).cumsum(axis=0)
data = pd.DataFrame(data, columns=pd.Index(['a', 'b', 'c', 'd'], name='label'))

# Figure
gs = pplt.GridSpec(ncols=2, nrows=2)
fig = pplt.figure(refwidth=2.2, share='labels', span=False)

# Vertical vs. horizontal
ax = fig.subplot(gs[0], title='Dependent x-axis')
ax.scatter(data, cycle='538')
ax = fig.subplot(gs[1], title='Dependent y-axis')
ax.scatterx(data, cycle='538')

# Scatter plot with property cycler
ax = fig.subplot(gs[2], title='With property cycle')
obj = ax.scatter(
    x, data, legend='ul', legend_kw={'ncols': 2},
    cycle='Set2', cycle_kw={'m': ['x', 'o', 'x', 'o'], 'ms': [5, 10, 20, 30]}
)

# Scatter plot with colormap
ax = fig.subplot(gs[3], title='With colormap')
data = state.rand(2, 100)
obj = ax.scatter(
    *data,
    s=state.rand(100), smin=6, smax=60, marker='o',
    c=data.sum(axis=0), cmap='maroon',
    colorbar='lr', colorbar_kw={'label': 'label'},
)
fig.format(suptitle='Scatter plot demo', xlabel='xlabel', ylabel='ylabel')

Parametric plots

Parametric plots can be drawn using the new parametric command. This creates LineCollections that map individual line segments to individual colors, where each segment represents a “parametric” coordinate (e.g., time). The parametric coordinates are specified with a third positional argument or with the keywords c, color, colors or values. Representing parametric coordinates with colors instead of text labels can be cleaner. The below example makes a simple parametric plot with a colorbar indicating the parametric coordinate.

import proplot as pplt
import numpy as np
import pandas as pd
gs = pplt.GridSpec(ncols=2, wratios=(2, 1))
fig = pplt.figure(figwidth='16cm', refaspect=(2, 1), share=False)
fig.format(suptitle='Parametric plots demo')
cmap = 'IceFire'

# Sample data
state = np.random.RandomState(51423)
N = 50
x = (state.rand(N) - 0.52).cumsum()
y = state.rand(N)
c = np.linspace(-N / 2, N / 2, N)  # color values
c = pd.Series(c, name='parametric coordinate')

# Parametric line with smooth gradations
ax = fig.subplot(gs[0])
m = ax.parametric(
    x, y, c, interp=10, capstyle='round', joinstyle='round',
    lw=7, cmap=cmap, colorbar='b', colorbar_kw={'locator': 5}
)
ax.format(xlabel='xlabel', ylabel='ylabel', title='Line with smooth gradations')

# Sample data
N = 12
radii = np.linspace(1, 0.2, N + 1)
angles = np.linspace(0, 4 * np.pi, N + 1)
x = radii * np.cos(1.4 * angles)
y = radii * np.sin(1.4 * angles)
c = np.linspace(-N / 2, N / 2, N + 1)

# Parametric line with stepped gradations
ax = fig.subplot(gs[1])
m = ax.parametric(x, y, c, cmap=cmap, lw=15)
ax.format(
    xlim=(-1, 1), ylim=(-1, 1), title='Step gradations',
    xlabel='cosine angle', ylabel='sine angle'
)
ax.colorbar(m, loc='b', locator=2, label='parametric coordinate')

<matplotlib.colorbar.Colorbar at 0x7f6e8735abe0>

Bar plots and area plots

The bar and barh commands apply default x or y coordinates if you failed to provide them explicitly and can group or stack successive columns of data if you pass 2D arrays instead of 1D arrays – just like pandas. When bars are grouped, their widths and positions are adjusted according to the number of bars in the group. Grouping is the default behavior and stacking can be enabled with stack=True or stacked=True.

The fill_between and fill_betweenx commands have the new shorthands area and areax. Similar to bar and barh, they apply default x coordinates if you failed to provide them explicitly, and can overlay or stack successive columns of data if you pass 2D arrays instead of 1D arrays – just like pandas. Overlaying is the default behavior but stacking can be enabled with stack=True or stacked=True. Also note the default x bounds for shading drawn with area and y bounds for shading drawn with areax is now “sticky”, i.e. there is no padding between the shading and axes edges by default.

Important

In matplotlib, bar widths for horizontal barh plots are expressed with the height keyword. In proplot, bar widths are always expressed with the width keyword. Note that bar widths can also be passed as a third positional argument. Additionally, matplotlib bar widths are always expressed in data units, while proplot bar widths are expressed in step size-relative units by default. For example, width=1 with a dependent coordinate step size of 2 fills 100% of the space between each bar rather than 50%. This can be disabled by passing absolute_width=True to bar or barh. This is done automatically when seaborn calls bar or barh internally.

import proplot as pplt
import numpy as np
import pandas as pd

# Sample data
state = np.random.RandomState(51423)
data = state.rand(5, 5).cumsum(axis=0).cumsum(axis=1)[:, ::-1]
data = pd.DataFrame(
    data, columns=pd.Index(np.arange(1, 6), name='column'),
    index=pd.Index(['a', 'b', 'c', 'd', 'e'], name='row idx')
)

# Figure
pplt.rc.abc = 'a.'
pplt.rc.titleloc = 'l'
gs = pplt.GridSpec(nrows=2, hratios=(3, 2))
fig = pplt.figure(refaspect=2, refwidth=4.8, share=False)

# Side-by-side bars
ax = fig.subplot(gs[0], title='Side-by-side')
obj = ax.bar(
    data, cycle='Reds', edgecolor='red9', colorbar='ul', colorbar_kw={'frameon': False}
)
ax.format(xlocator=1, xminorlocator=0.5, ytickminor=False)

# Stacked bars
ax = fig.subplot(gs[1], title='Stacked')
obj = ax.barh(
    data.iloc[::-1, :], cycle='Blues', edgecolor='blue9', legend='ur', stack=True,
)
fig.format(grid=False, suptitle='Bar plot demo')
pplt.rc.reset()

import proplot as pplt
import numpy as np

# Sample data
state = np.random.RandomState(51423)
data = state.rand(5, 3).cumsum(axis=0)
cycle = ('gray3', 'gray5', 'gray7')

# Figure
pplt.rc.abc = 'a.'
pplt.rc.titleloc = 'l'
fig = pplt.figure(refwidth=2.3, share=False)

# Overlaid area patches
ax = fig.subplot(121, title='Fill between columns')
ax.area(
    np.arange(5), data, data + state.rand(5)[:, None], cycle=cycle, alpha=0.7,
    legend='uc', legend_kw={'center': True, 'ncols': 2, 'labels': ['z', 'y', 'qqqq']},
)

# Stacked area patches
ax = fig.subplot(122, title='Stack between columns')
ax.area(
    np.arange(5), data, stack=True, cycle=cycle, alpha=0.8,
    legend='ul', legend_kw={'center': True, 'ncols': 2, 'labels': ['z', 'y', 'qqqq']},
)
fig.format(grid=False, xlabel='xlabel', ylabel='ylabel', suptitle='Area plot demo')
pplt.rc.reset()

Negative and positive colors

You can use different colors for “negative” and “positive” data by passing negpos=True to any of the fill_between, fill_betweenx (shorthands area, areax), vlines, hlines, bar, or barh commands. The default negative and positive colors are controlled with rc.negcolor and rc.poscolor but the colors can be modified for particular plots by passing negcolor=color and poscolor=color to the PlotAxes commands.

import proplot as pplt
import numpy as np

# Sample data
state = np.random.RandomState(51423)
data = 4 * (state.rand(40) - 0.5)

# Figure
pplt.rc.abc = 'a.'
pplt.rc.titleloc = 'l'
fig, axs = pplt.subplots(nrows=3, refaspect=2, figwidth=5)
axs.format(
    xmargin=0, xlabel='xlabel', ylabel='ylabel', grid=True,
    suptitle='Positive and negative colors demo',
)
for ax in axs:
    ax.axhline(0, color='k', linewidth=1)  # zero line

# Line plot
ax = axs[0]
ax.vlines(data, linewidth=3, negpos=True)
ax.format(title='Line plot')

# Bar plot
ax = axs[1]
ax.bar(data, width=1, negpos=True, edgecolor='k')
ax.format(title='Bar plot')

# Area plot
ax = axs[2]
ax.area(data, negpos=True, lw=0.5, edgecolor='k')
ax.format(title='Area plot')

# Reset title styles changed above
pplt.rc.reset()