How to have clusters of stacked bars with python (

问题:

So here is how my data set looks like :

In [1]: df1=pd.DataFrame(np.random.rand(4,2),index=["A","B","C","D"],columns=["I","J"])

In [2]: df2=pd.DataFrame(np.random.rand(4,2),index=["A","B","C","D"],columns=["I","J"])

In [3]: df1
Out[3]: 
          I         J
A  0.675616  0.177597
B  0.675693  0.598682
C  0.631376  0.598966
D  0.229858  0.378817

In [4]: df2
Out[4]: 
          I         J
A  0.939620  0.984616
B  0.314818  0.456252
C  0.630907  0.656341
D  0.020994  0.538303

I want to have stacked bar plot for each dataframe but since they have same index, I'd like to have 2 stacked bars per index.

I've tried to plot both on the same axes :

In [5]: ax = df1.plot(kind="bar", stacked=True)

In [5]: ax2 = df2.plot(kind="bar", stacked=True, ax = ax)

But it overlaps.

Then I tried to concat the two dataset first :

pd.concat(dict(df1 = df1, df2 = df2),axis = 1).plot(kind="bar", stacked=True)

but here everything is stacked

My best try is :

 pd.concat(dict(df1 = df1, df2 = df2),axis = 0).plot(kind="bar", stacked=True)

Which gives :

This is basically what I want, except that I want the bar ordered as

(df1,A) (df2,A) (df1,B) (df2,B) etc...

I guess there is a trick but I can't found it !

---

After @bgschiller's answer I got this :

Which is almost what I want. I would like the bar to be clustered by index, in order to have something visually clear.

Bonus : Having the x-label not redundant, something like :

df1 df2    df1 df2
_______    _______ ...
   A          B

Thanks for helping.

回答1:

So, I eventually found a trick (edit: see below for using seaborn and longform dataframe):

Solution with pandas and matplotlib

Here it is with a more complete example :

import pandas as pd
import matplotlib.cm as cm
import numpy as np
import matplotlib.pyplot as plt

def plot_clustered_stacked(dfall, labels=None, title="multiple stacked bar plot",  H="/", **kwargs):
    """Given a list of dataframes, with identical columns and index, create a clustered stacked bar plot. 
labels is a list of the names of the dataframe, used for the legend
title is a string for the title of the plot
H is the hatch used for identification of the different dataframe"""

    n_df = len(dfall)
    n_col = len(dfall[0].columns) 
    n_ind = len(dfall[0].index)
    axe = plt.subplot(111)

    for df in dfall : # for each data frame
        axe = df.plot(kind="bar",
                      linewidth=0,
                      stacked=True,
                      ax=axe,
                      legend=False,
                      grid=False,
                      **kwargs)  # make bar plots

    h,l = axe.get_legend_handles_labels() # get the handles we want to modify
    for i in range(0, n_df * n_col, n_col): # len(h) = n_col * n_df
        for j, pa in enumerate(h[i:i+n_col]):
            for rect in pa.patches: # for each index
                rect.set_x(rect.get_x() + 1 / float(n_df + 1) * i / float(n_col))
                rect.set_hatch(H * int(i / n_col)) #edited part     
                rect.set_width(1 / float(n_df + 1))

    axe.set_xticks((np.arange(0, 2 * n_ind, 2) + 1 / float(n_df + 1)) / 2.)
    axe.set_xticklabels(df.index, rotation = 0)
    axe.set_title(title)

    # Add invisible data to add another legend
    n=[]        
    for i in range(n_df):
        n.append(axe.bar(0, 0, color="gray", hatch=H * i))

    l1 = axe.legend(h[:n_col], l[:n_col], loc=[1.01, 0.5])
    if labels is not None:
        l2 = plt.legend(n, labels, loc=[1.01, 0.1]) 
    axe.add_artist(l1)
    return axe

# create fake dataframes
df1 = pd.DataFrame(np.random.rand(4, 5),
                   index=["A", "B", "C", "D"],
                   columns=["I", "J", "K", "L", "M"])
df2 = pd.DataFrame(np.random.rand(4, 5),
                   index=["A", "B", "C", "D"],
                   columns=["I", "J", "K", "L", "M"])
df3 = pd.DataFrame(np.random.rand(4, 5),
                   index=["A", "B", "C", "D"], 
                   columns=["I", "J", "K", "L", "M"])

# Then, just call :
plot_clustered_stacked([df1, df2, df3],["df1", "df2", "df3"])

And it gives that :

You can change the colors of the bar by passing a cmap argument:

plot_clustered_stacked([df1, df2, df3],
                       ["df1", "df2", "df3"],
                       cmap=plt.cm.viridis)

---

Solution with seaborn:

Given the same df1, df2, df3, below, I convert them in a long form:

df1["Name"] = "df1"
df2["Name"] = "df2"
df3["Name"] = "df3"
dfall = pd.concat([pd.melt(i.reset_index(),
                           id_vars=["Name", "index"]) # transform in tidy format each df
                   for i in [df1, df2, df3]],
                   ignore_index=True)

The problem with seaborn is that it doesn't stack bars natively, so the trick is to plot the cumulative sum of each bar on top of each other:

dfall.set_index(["Name", "index", "variable"], inplace=1)
dfall["vcs"] = dfall.groupby(level=["Name", "index"]).cumsum()
dfall.reset_index(inplace=True) 

>>> dfall.head(6)
  Name index variable     value       vcs
0  df1     A        I  0.717286  0.717286
1  df1     B        I  0.236867  0.236867
2  df1     C        I  0.952557  0.952557
3  df1     D        I  0.487995  0.487995
4  df1     A        J  0.174489  0.891775
5  df1     B        J  0.332001  0.568868

Then loop over each group of variable and plot the cumulative sum:

c = ["blue", "purple", "red", "green", "pink"]
for i, g in enumerate(dfall.groupby("variable")):
    ax = sns.barplot(data=g[1],
                     x="index",
                     y="vcs",
                     hue="Name",
                     color=c[i],
                     zorder=-i, # so first bars stay on top
                     edgecolor="k")
ax.legend_.remove() # remove the redundant legends 

It lacks the legend that can be added easily I think. The problem is that instead of hatches (which can be added easily) to differentiate the dataframes we have a gradient of lightness, and it's a bit too light for the first one, and I don't really know how to change that without changing each rectangle one by one (as in the first solution).

Tell me if you don't understand something in the code.

Feel free to re-use this code which is under CC0.

回答2:

I have managed to do the same using pandas and matplotlib subplots with basic commands.

Here's an example:

fig, axes = plt.subplots(nrows=1, ncols=3)

ax_position = 0
for concept in df.index.get_level_values('concept').unique():
    idx = pd.IndexSlice
    subset = df.loc[idx[[concept], :],
                    ['cmp_tr_neg_p_wrk', 'exp_tr_pos_p_wrk',
                     'cmp_p_spot', 'exp_p_spot']]     
    print(subset.info())
    subset = subset.groupby(
        subset.index.get_level_values('datetime').year).sum()
    subset = subset / 4  # quarter hours
    subset = subset / 100  # installed capacity
    ax = subset.plot(kind="bar", stacked=True, colormap="Blues",
                     ax=axes[ax_position])
    ax.set_title("Concept \"" + concept + "\"", fontsize=30, alpha=1.0)
    ax.set_ylabel("Hours", fontsize=30),
    ax.set_xlabel("Concept \"" + concept + "\"", fontsize=30, alpha=0.0),
    ax.set_ylim(0, 9000)
    ax.set_yticks(range(0, 9000, 1000))
    ax.set_yticklabels(labels=range(0, 9000, 1000), rotation=0,
                       minor=False, fontsize=28)
    ax.set_xticklabels(labels=['2012', '2013', '2014'], rotation=0,
                       minor=False, fontsize=28)
    handles, labels = ax.get_legend_handles_labels()
    ax.legend(['Market A', 'Market B',
               'Market C', 'Market D'],
              loc='upper right', fontsize=28)
    ax_position += 1

# look "three subplots"
#plt.tight_layout(pad=0.0, w_pad=-8.0, h_pad=0.0)

# look "one plot"
plt.tight_layout(pad=0., w_pad=-16.5, h_pad=0.0)
axes[1].set_ylabel("")
axes[2].set_ylabel("")
axes[1].set_yticklabels("")
axes[2].set_yticklabels("")
axes[0].legend().set_visible(False)
axes[1].legend().set_visible(False)
axes[2].legend(['Market A', 'Market B',
                'Market C', 'Market D'],
               loc='upper right', fontsize=28)

The dataframe structure of "subset" before grouping looks like this:

<class 'pandas.core.frame.DataFrame'>
MultiIndex: 105216 entries, (D_REC, 2012-01-01 00:00:00) to (D_REC, 2014-12-31 23:45:00)
Data columns (total 4 columns):
cmp_tr_neg_p_wrk    105216 non-null float64
exp_tr_pos_p_wrk    105216 non-null float64
cmp_p_spot          105216 non-null float64
exp_p_spot          105216 non-null float64
dtypes: float64(4)
memory usage: 4.0+ MB

and the plot like this:

It is formatted in the "ggplot" style with the following header:

import pandas as pd
import matplotlib.pyplot as plt
import matplotlib
matplotlib.style.use('ggplot')

回答3:

This is a great start but I think the colors could be modified a bit for clarity. Also be careful about importing every argument in Altair as this may cause collisions with existing objects in your namespace. Here is some reconfigured code to display the correct color display when stacking the values:

Import packages

import pandas as pd
import numpy as np
import altair as alt

Generate some random data

df1=pd.DataFrame(10*np.random.rand(4,3),index=["A","B","C","D"],columns=["I","J","K"])
df2=pd.DataFrame(10*np.random.rand(4,3),index=["A","B","C","D"],columns=["I","J","K"])
df3=pd.DataFrame(10*np.random.rand(4,3),index=["A","B","C","D"],columns=["I","J","K"])

def prep_df(df, name):
    df = df.stack().reset_index()
    df.columns = ['c1', 'c2', 'values']
    df['DF'] = name
    return df

df1 = prep_df(df1, 'DF1')
df2 = prep_df(df2, 'DF2')
df3 = prep_df(df3, 'DF3')

df = pd.concat([df1, df2, df3])

Plot data with Altair

alt.Chart(df).mark_bar().encode(

    # tell Altair which field to group columns on
    x=alt.X('c2:N', title=None),

    # tell Altair which field to use as Y values and how to calculate
    y=alt.Y('sum(values):Q',
        axis=alt.Axis(
            grid=False,
            title=None)),

    # tell Altair which field to use to use as the set of columns to be  represented in each group
    column=alt.Column('c1:N', title=None),

    # tell Altair which field to use for color segmentation 
    color=alt.Color('DF:N',
            scale=alt.Scale(
                # make it look pretty with an enjoyable color pallet
                range=['#96ceb4', '#ffcc5c','#ff6f69'],
            ),
        ))\
    .configure_view(
        # remove grid lines around column clusters
        strokeOpacity=0    
    )

回答4:

The answer by @jrjc for use of seaborn is very clever, but it has a few problems, as noted by the author:

1. The "light" shading is too pale when only two or three categories are needed. It makes colour series (pale blue, blue, dark blue, etc.) difficult to distinguish.
2. The legend is not produced to distinguish the meaning of the shadings ("pale" means what?)

More importantly, however, I found out that, because of the groupbystatement in the code:

3. This solution works only if the columns are ordered alphabetically. If I rename columns ["I", "J", "K", "L", "M"] by something anti-alphabetical (["zI", "yJ", "xK", "wL", "vM"]), I get this graph instead:

---

I strove to resolve these problems with the plot_grouped_stackedbars() function in this open-source python module.

1. It keeps the shading within reasonable range
2. It auto-generates a legend that explains the shading
3. It does not rely on groupby

It also allows for

1. various normalization options (see below normalization to 100% of maximum value)
2. the addition of error bars

See full demo here. I hope this proves useful and can answer the original question.

回答5:

You're on the right track! In order to change the order of the bars, you should change the order in the index.

In [5]: df_both = pd.concat(dict(df1 = df1, df2 = df2),axis = 0)

In [6]: df_both
Out[6]:
              I         J
df1 A  0.423816  0.094405
    B  0.825094  0.759266
    C  0.654216  0.250606
    D  0.676110  0.495251
df2 A  0.607304  0.336233
    B  0.581771  0.436421
    C  0.233125  0.360291
    D  0.519266  0.199637

[8 rows x 2 columns]

So we want to swap axes, then reorder. Here's an easy way to do this

In [7]: df_both.swaplevel(0,1)
Out[7]:
              I         J
A df1  0.423816  0.094405
B df1  0.825094  0.759266
C df1  0.654216  0.250606
D df1  0.676110  0.495251
A df2  0.607304  0.336233
B df2  0.581771  0.436421
C df2  0.233125  0.360291
D df2  0.519266  0.199637

[8 rows x 2 columns]

In [8]: df_both.swaplevel(0,1).sort_index()
Out[8]:
              I         J
A df1  0.423816  0.094405
  df2  0.607304  0.336233
B df1  0.825094  0.759266
  df2  0.581771  0.436421
C df1  0.654216  0.250606
  df2  0.233125  0.360291
D df1  0.676110  0.495251
  df2  0.519266  0.199637

[8 rows x 2 columns]

If it's important that your horizontal labels show up in the old order (df1,A) rather than (A,df1), we can just swaplevels again and not sort_index:

In [9]: df_both.swaplevel(0,1).sort_index().swaplevel(0,1)
Out[9]:
              I         J
df1 A  0.423816  0.094405
df2 A  0.607304  0.336233
df1 B  0.825094  0.759266
df2 B  0.581771  0.436421
df1 C  0.654216  0.250606
df2 C  0.233125  0.360291
df1 D  0.676110  0.495251
df2 D  0.519266  0.199637

[8 rows x 2 columns]

回答6:

Altair can be helpful here. Here is the produced plot.

Imports

import pandas as pd
import numpy as np
from altair import *

Dataset creation

df1=pd.DataFrame(10*np.random.rand(4,2),index=["A","B","C","D"],columns=["I","J"])
df2=pd.DataFrame(10*np.random.rand(4,2),index=["A","B","C","D"],columns=["I","J"])

Preparing dataset

def prep_df(df, name):
    df = df.stack().reset_index()
    df.columns = ['c1', 'c2', 'values']
    df['DF'] = name
    return df

df1 = prep_df(df1, 'DF1')
df2 = prep_df(df2, 'DF2')

df = pd.concat([df1, df2])

Altair plot

Chart(df).mark_bar().encode(y=Y('values', axis=Axis(grid=False)),
                            x='c2:N', 
                            column=Column('c1:N') ,
                            color='DF:N').configure_facet_cell( strokeWidth=0.0).configure_cell(width=200, height=200)

回答7:

I liked the solution of Cord Kaldemeyer, but it is not robust at all (and contain some useless lines). Here is a modified version. The idea is to reserve as much width as necessary for the plots. Then each cluster gets a subplot of the required length.

# Data and imports

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np
from matplotlib.ticker import MaxNLocator
import matplotlib.gridspec as gridspec
import matplotlib

matplotlib.style.use('ggplot')

np.random.seed(0)

df = pd.DataFrame(np.asarray(1+5*np.random.random((10,4)), dtype=int),columns=["Cluster", "Bar", "Bar_part", "Count"])
df = df.groupby(["Cluster", "Bar", "Bar_part"])["Count"].sum().unstack(fill_value=0)
display(df)

# plotting

clusters = df.index.levels[0]
inter_graph = 0
maxi = np.max(np.sum(df, axis=1))
total_width = len(df)+inter_graph*(len(clusters)-1)

fig = plt.figure(figsize=(total_width,10))
gridspec.GridSpec(1, total_width)
axes=[]

ax_position = 0
for cluster in clusters:
    subset = df.loc[cluster]
    ax = subset.plot(kind="bar", stacked=True, width=0.8, ax=plt.subplot2grid((1,total_width), (0,ax_position), colspan=len(subset.index)))
    axes.append(ax)
    ax.set_title(cluster)
    ax.set_xlabel("")
    ax.set_ylim(0,maxi+1)
    ax.yaxis.set_major_locator(MaxNLocator(integer=True))
    ax_position += len(subset.index)+inter_graph

for i in range(1,len(clusters)):
    axes[i].set_yticklabels("")
    axes[i-1].legend().set_visible(False)
axes[0].set_ylabel("y_label")

fig.suptitle('Big Title', fontsize="x-large")
legend = axes[-1].legend(loc='upper right', fontsize=16, framealpha=1).get_frame()
legend.set_linewidth(3)
legend.set_edgecolor("black")

plt.show()

The result is the following:

(not able yet to post an image directly on the site)