The examples didn't manage unequal # of bars but you can use another approach. I'll post you an example.
Note: I use pandas to manipulate your data, if you don't know about it you should give it a try http://pandas.pydata.org/:
import pandas as pd
import matplotlib.pyplot as plt
import matplotlib.ticker as mtick
import numpy as np
df = pd.read_table("data.csv",sep="|")
grouped = df.groupby('app')['hours']
colors = "rgbcmyk"
fig, ax = plt.subplots()
initial_gap = 0.1
start = initial_gap
width = 1.0
gap = 0.05
for app,group in grouped:
size = group.shape[0]
ind = np.linspace(start,start + width, size+1)[:-1]
w = (ind[1]-ind[0])
start = start + width + gap
plt.bar(ind,group,w,color=list(colors[:size]))
tick_loc = (np.arange(len(grouped)) * (width+gap)) + initial_gap + width/2
ax.set_xticklabels([app for app,_ in grouped])
ax.xaxis.set_major_locator(mtick.FixedLocator(tick_loc))
plt.show()
And on data.csv is the data:
date|name|empid|app|subapp|hours
20140101|A|0001|IIC|I1|2.5
20140101|A|0001|IIC|I2|3
20140101|A|0001|IIC|I3|4
20140101|A|0001|CAR|C1|2.5
20140101|A|0001|CAR|C2|3
20140101|A|0001|CAR|C3|2
20140101|A|0001|CAR|C4|2