Pandas DataFrame column numerical integration

Question

Currently I have a DataFrame as shown below:

Device   TimeSec  Current  
 1       0.1      0.02
 1       0.25     0.05
 1       0.32     0.07
 1       0.45     0.12
 1       1.32     0.34
 1       2.37     2.24
 2       0.22     0.56
 2       0.34     0.79
 2       1.87     2.76
 2       3.21     3.11
 3       0.16     1.87
 3       1.12     2.33
 3       2.45     3.21
 3       3.45     5.11
 ......

I would like to do the numerical integration of Current with TimeSec (∫Idt) for different Devices and collect the data into a new DataFrame as below:

Device   IntegratedCurrent  
 1         x
 2         y
 3         z

The problem is that the time interval is not even and the number of data for each device is not even as well.

Many thanks!

Answer 1

Use some numerical integration function, e.g., scipy.integrate.trapz:

from scipy import integrate

df.groupby(df.Device).apply(lambda g: integrate.trapz(g.Current, x=g.TimeSec))

Note that this function, using the trapezoid integration rule, allows to specify the x values.