# create a boxplot of yearly data
from pandas import read_csv
from pandas import DataFrame
from pandas import Grouper
from matplotlib import pyplot

filename = 'daily-minimum-temperatures.csv'
series = read_csv(filename, header=0, index_col=0, parse_dates=True, squeeze=True)
groups = series.groupby(Grouper(freq='A'))
years = DataFrame()
for name, group in groups:
    years[name.year] = group.values
years.boxplot()
pyplot.show()