Annotate bars with values on Pandas bar plots

I was looking for a way to annotate my bars in a Pandas bar plot with the rounded numerical values from my DataFrame.

>>> df=pd.DataFrame({'A':np.random.rand(2),'B':np.random.rand(2)},index=['value1','value2'] )         
>>> df
                 A         B
  value1  0.440922  0.911800
  value2  0.588242  0.797366

I would like to get something like this:

I tried with this code sample, but the annotations are all centered on the x ticks:

>>> ax = df.plot(kind='bar') 
>>> for idx, label in enumerate(list(df.index)): 
        for acc in df.columns:
            value = np.round(df.ix[idx][acc],decimals=2)
            ax.annotate(value,
                        (idx, value),
                         xytext=(0, 15), 
                         textcoords='offset points')

You get it directly from the axes' patches:

for p in ax.patches:
    ax.annotate(str(p.get_height()), (p.get_x() * 1.005, p.get_height() * 1.005))

You'll want to tweak the string formatting and the offsets to get things centered, maybe use the width from p.get_width(), but that should get you started. It may not work with stacked bar plots unless you track the offsets somewhere.

Solution which also handles the negative values with sample float formatting.

Still needs tweaking offsets.

df=pd.DataFrame({'A':np.random.rand(2)-1,'B':np.random.rand(2)},index=['val1','val2'] )
ax = df.plot(kind='bar', color=['r','b']) 
x_offset = -0.03
y_offset = 0.02
for p in ax.patches:
    b = p.get_bbox()
    val = "{:+.2f}".format(b.y1 + b.y0)        
    ax.annotate(val, ((b.x0 + b.x1)/2 + x_offset, b.y1 + y_offset))