Examples: Temperature

Temperature of the Rhine at Lobith

Yearly averages of the water temperature of the Rhine at Lobith.
Author: Do Kester

We need to import some classes

In[1]:

import numpy as numpy

from astropy.io import ascii
import matplotlib.pyplot as plt

from BayesicFitting import PolynomialModel
from BayesicFitting import Fitter
from BayesicFitting import formatter as fmt

Read the data. Subtract 1900 to get ``nicer'' data during the fit.

In[2]:

tbl = ascii.read( "data/temp-rijn.txt" )
jr = tbl['Jaar'].data
te = tbl['gemiddelde'].data
jr -= 1900

Make a model: a Polynomial of order 2

In[3]:

mdl = PolynomialModel( 2 )
print( mdl )

Out[3]:

Polynomial: f( x:p ) = p_0 + p_1 * x + p_2 * x^2

Select a fitter.

In[5]:

ftr = Fitter( jr, mdl )

par = ftr.fit( te )

print( "params :", fmt( par ) )
print( "stdevs :", fmt( ftr.stdevs ) )

Out[5]:

params : [   10.410    0.028    0.000]
stdevs : [    0.230    0.008    0.000]

In[6]:

#plt.plot( jr + 1900, te, 'k. ' )
xx = numpy.linspace( 0, 120, 121, dtype=float )
yfit = mdl( xx )
yerr = ftr.monteCarloError( xdata=xx )


fig, ax = plt.subplots()
ax.plot(xx+1900, yfit, 'r-')
ax.fill_between( xx+1900, yfit - yerr, yfit + yerr, color='b' )
ax.plot(jr+1900, te, 'k.')


plt.xlabel( "Year")
plt.ylabel( "Temperature")
plt.title( "Water of the Rhine" )
plt.show()

Temperature