print "Reading samples from %s" % (logfile)

time_samples = []

h_samples = []

t_samples = []

f = open(logfile)

for line in f:

# Lines are of the following form:

# <timestamp><TAB><humidity><TAB><temperature>

line = line.strip()

if not line or line.startswith('#'):

continue

ts, humd, temp = line.split("\t")

ts = datetime.strptime(ts, "%Y-%m-%dT%H:%M:%S")

humd = float(humd)

temp = float(temp)

time_samples.append(ts)

h_samples.append(humd)

t_samples.append(temp)

f.close()

# Time

start_ts = time_samples[0]

end_ts = time_samples[-1]

diff = end_ts - start_ts

elapsed = ""

if diff.days:

elapsed = "%u days, " % (diff.days)

seconds = diff.seconds % 60

minutes = (diff.seconds // 60) % 60

hours = diff.seconds / (60 * 60)

elapsed += "%02u:%02u:%02u" % (hours, minutes, seconds)

# Humidity

h_max = h_min = None

h_sum = 0

for h in h_samples:

h_sum += h

if h < h_min or h_min is None:

h_min = h

if h > h_max or h_max is None:

h_max = h

h_avg = h_sum / len(h_samples)

# Temperature

t_max = t_min = None

t_sum = 0

for t in t_samples:

t_sum += t

if t < t_min or t_min is None:

t_min = t

if t > t_max or t_max is None:

t_max = t

t_avg = t_sum / len(t_samples)

# Output analysis

print "Read %u samples from between %s and %s (%s)" % (

len(time_samples), start_ts.isoformat(" "),

end_ts.isoformat(" "), elapsed)

print "Min/Avg/Max humidity: %2.2f/%2.2f/%2.2f %%" % (

h_min, h_avg, h_max)

print "Min/Avg/Max temperature: %2.2f/%2.2f/%2.2f C" % (

t_min, t_avg, t_max)

# Draw gnuplot graph

g = Gnuplot.Gnuplot()

g('set term svg size 1920,1080 dynamic')

g('set out "%s.svg"' % (logfile))

g('set title "Relative humidity/temperature readings from %s to %s \\n'

'(%u samples over %s)"' % (

start_ts.isoformat(" "), end_ts.isoformat(" "),

len(time_samples), elapsed))

g('set xlabel "Time"')

g('set ylabel "Humidity [%]"')

g('set y2label "Temperature [C]"')

g('set ytics nomirror')

g('set yrange [0 : 100]')

g('set ytics 10 10')

g('set mytics 2')

g('set y2range [0 : 50]')

g('set y2tics 0, 5')

g('set my2tics 5')

g('set grid x y')

g('set xdata time')

g('set timefmt "%Y-%m-%dT%H:%M:%S"')

g('plot "%s" using 1:2 axis x1y1 title "Humidity [%%]" with lines,'

'30 axis x1y1 title "Min. comfortable humidity (30%%)" with lines,'

'40 axis x1y1 title "Nom. comfortable humidity (40%%)" with lines,'

'50 axis x1y1 title "Max. comfortable humidity (50%%)" with lines,'

'"%s" using 1:3 axis x1y2 title "Temperature [C]" with lines'