[Matplotlib-users] BrokenBarHCollection with pandas timeseries

[Fabien <fab...@gm...>]

Folks,

I'm trying to use BrokenBarHCollection with pandas timeseries object.

Here's a minimal example: (python 3.3, pandas 0.15.1, matplotlib 1.4.2)

#-----------------------------------------------------
import pandas as pd
import numpy as np
from datetime import datetime as dt
import matplotlib.pyplot as plt
import matplotlib.collections as collections
span_where = collections.BrokenBarHCollection.span_where

# init the dataframe
time = pd.date_range(pd.datetime(1950,1,1), periods=5, freq='MS')
df = pd.DataFrame(np.arange(5), index=time, columns=['data'])
df['cond'] = df['data'] == 3

# Make the plot
fig = plt.figure()
ax = fig.add_subplot(111)
df['data'].plot(ax=ax, c='black')
c = span_where(df.index, ymin=0, ymax=4, where=df['cond'], 
facecolor='green', alpha=0.5)
#-----------------------------------------------------

I get the error:
"TypeError: float() argument must be a string or a number"

Basically, span_where() is not happy with my x values which are a panda 
timeserie. I tried several stuffs (df.index.to_*) but there is something 
I still don't get in the internal representation of dates in matplolib.

Any hint? Thanks a lot!

Fabien