Python – pandas .loc returns an empty data frame

I have a pandas data frame as shown below.

chainage(km)  
0  
0.001  
0.002  
0.003  
0.004

When I search chainage(km) using .loc, it returns an empty dataframe for some mileage.

print data.loc[data['chainage(km)'] == float(0.004)]  

— Empty data frame

print data.loc[data['chainage(km)'] == float(0.001)]  

— Return value

Any help would be appreciated.

The problem is caused by inaccurate floats. This is explained in Is floating point math broken?

In this case, use np.isclose instead.

df[np.isclose(data['chainage(km)'], 0.004)]