Seasonal adjustment in Python and Scipy

Question

I am looking to seasonally adjust monthly data, using Python. As you can see from these series: www.emconfidential.com, there is a high seasonal component to the data. I would like to adjust for this so that I can better guage if the series trend is rising or falling. Anybody know how to do this easily using scipy or other Python library?

Answer 1

Statsmodels can do this. They have a basic seasonal decomposition and also a wrapper to Census X13 adjustment. You could also use rpy2 to access some of R's excellent SA libraries. Here is statsmodels seasonal decomp:

import pandas as pd
import statsmodels.api as sm
import matplotlib.pyplot as plt
pd.options.display.mpl_style = 'default'
%matplotlib inline

dta = sm.datasets.co2.load_pandas().data.resample("M").fillna(method="ffill")

res = sm.tsa.seasonal_decompose(dta)

fig = res.plot()
fig.set_size_inches(10, 5)
plt.tight_layout()

http://statsmodels.sourceforge.net/0.6.0/release/version0.6.html