# Berendsen's code 2.5 for Fig.2.6

import matplotlib.pyplot as plt
import numpy as np 

time = np.array([20., 40., 60., 80., 100., 120., 140., 160., 180])
conc = np.array([75., 43., 26., 16., 10., 5., 3.5, 1.8, 1.6])
err = np.array([4., 3., 3., 3., 2., 2., 1., 1., 1.])

fig, ax = plt.subplots()
ax.plot(time,conc,lw=2,ls='-',marker='o',ms=5,mec='r',mew=2,mfc='r')
ax.set_yscale('log')

pos = [1, 10, 100] 
# ax.set_yticks(pos)
# ticks = ['1', '10', '100']
# ax.set_yticklabels(ticks)

# plt.semilogy(time, conc)')
plt.errorbar(time, conc, err)
plt.grid(axis='y', which='both')
plt.grid(axis='x', which='major')

font1 = {'family':'serif','color':'blue','size':13}

plt.xlabel('time $t$/s',fontdict = font1 )
plt.ylabel('concentration $c$/mmol L$^{-1}$',fontdict = font1)
plt.title('Code 2.5 for Fig.2.7')

plt.show()
# fig.savefig('plot of fig.2.7.png')