mscroggs.co.uk
mscroggs.co.uk

subscribe

Blog

 2013-07-11 
On 19 June, the USB temperature sensor I ordered from Amazon arrived. This sensor is now hooked up to my Raspberry Pi, which is taking the temperature every 10 minutes, drawing graphs, then uploading them here. Here is a brief outline of how I set this up:

Reading the temperature

I found this code and adapted it to write the date, time and temperature to a text file. I then set cron to run this every 10 minutes. It writes the data to a text file (/var/www/temperature2) in this format:
2013 06 20 03 50,16.445019
2013 06 20 04 00,16.187843
2013 06 20 04 10,16.187843
2013 06 20 04 20,16.187843

Plotting the graphs

I found a guide somewhere on the internet about how to draw graphs with Python using Pylab/Matplotlib. If you have any idea where this could be, comment below and I'll put a link here.
In the end my code looked like this:
 python 
import time
import matplotlib as mpl
mpl.use("Agg")
import matplotlib.pylab as plt
import matplotlib.dates as mdates

ts = time.time()
import datetime
now = datetime.datetime.fromtimestamp(ts)
st = mdates.date2num(datetime.datetime(int(float(now.strftime("%Y"))),
                                       int(float(now.strftime("%m"))),
                                       int(float(now.strftime("%d"))),
                                       0, 0, 0))
weekst = st - int(float(datetime.datetime.fromtimestamp(ts).strftime("%w")))
= file("/var/www/temperature2","r")
= []
= []
tt = []
ss = []
= []
= []
= []
= []
= []
weekt = []
weektt = []
weeks = []
weekss = []
mini = 1000
maxi = 0
cur = -1
datC = 0

for line in f:
    fL = line.split(",")
    fL[0] = fL[0].split(" ")
    if cur == -1:
        cur = mdates.date2num(datetime.datetime(int(float(fL[0][0])),
                                                int(float(fL[0][1])),
                                                int(float(fL[0][2])),
                                                0,0,0))
        datC = mdates.date2num(datetime.datetime(int(float(fL[0][0])),
                                                 int(float(fL[0][1])),
                                                 int(float(fL[0][2])),
                                                 int(float(fL[0][3])),
                                                 int(float(fL[0][4])),
                                                 0))
    u.append(datC)
    v.append(fL[1])
    if datC >= st and datC <= st + 1:
        t.append(datC)
        s.append(fL[1])
    if datC >= st - 1 and datC <= st:
        tt.append(datC + 1)
        ss.append(fL[1])
    if datC >= weekst and datC <= weekst + 7:
        weekt.append(datC)
        weeks.append(fL[1])
    if datC >= weekst - 7 and datC <= weekst:
        weektt.append(datC + 7)
        weekss.append(fL[1])
    if datC > cur + 1:
        g.append(cur)
        h.append(mini)
        i.append(maxi)
        mini = 1000
        maxi = 0
        cur = mdates.date2num(datetime.datetime(int(float(fL[0][0])),
                                                int(float(fL[0][1])),
                                                int(float(fL[0][2])),
                                                0,0,0))
    mini = min(float(fL[1]),mini)
    maxi = max(float(fL[1]),maxi)
g.append(cur)
h.append(mini)
i.append(maxi)

plt.plot_date(x=t,y=s,fmt="r-")
plt.plot_date(x=tt,y=ss,fmt="g-")
plt.xlabel("Time")
plt.ylabel("Temperature (#^\circ#C)")
plt.title("Daily")
plt.legend(["today","yesterday"], loc="upper left",prop={"size":8})
plt.grid(True)
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter("%H:%M"))
plt.gcf().subplots_adjust(bottom=0.15,right=0.99)
labels = plt.gca().get_xticklabels()
plt.setp(labels,rotation=90,fontsize=10)
plt.xlim(st,st + 1)
plt.savefig("/var/www/tempr/tg1p.png")

plt.clf()

plt.plot_date(x=weekt,y=weeks,fmt="r-")
plt.plot_date(x=weektt,y=weekss,fmt="g-")
plt.xlabel("Day")
plt.ylabel("Temperature (#^\circ#C)")
plt.title("Weekly")
plt.legend(["this week","last week"], loc="upper left",prop={"size":8})
plt.grid(True)
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter("                     %A"))
plt.gcf().subplots_adjust(bottom=0.15,right=0.99)
labels = plt.gca().get_xticklabels()
plt.setp(labels,rotation=0,fontsize=10)
plt.xlim(weekst,weekst + 7)
plt.savefig("/var/www/tempr/tg2p.png")

plt.clf()

plt.plot_date(x=u,y=v,fmt="r-")
plt.xlabel("Date & Time")
plt.ylabel("Temperature (#^\circ#C)")
plt.title("Forever")
plt.grid(True)
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter("%d/%m/%y %H:%M"))
plt.gcf().subplots_adjust(bottom=0.25,right=0.99)
labels = plt.gca().get_xticklabels()
plt.setp(labels,rotation=90,fontsize=8)
plt.savefig("/var/www/tempr/tg4p.png")


plt.clf()

plt.plot_date(x=g,y=h,fmt="b-")
plt.plot_date(x=g,y=i,fmt="r-")
plt.xlabel("Date")
plt.ylabel("Temperature (#^\circ#C)")
plt.title("Forever")
plt.legend(["minimum","maximum"], loc="upper left",prop={"size":8})
plt.grid(True)
plt.gca().xaxis.set_major_formatter(mdates.DateFormatter("%d %b"))
plt.gcf().subplots_adjust(bottom=0.15,right=0.99)
labels = plt.gca().get_xticklabels()
plt.setp(labels,rotation=90,fontsize=8)
plt.savefig("/var/www/tempr/tg3p.png")
If there's anything in there you don't understand, comment below and I'll try to fill in the gaps.

Uploading the graphs

Finally, I upload the graphs to mscroggs.co.uk/weather. To do this, I set up pre-shared keys on the Raspberry Pi and this server and added the following as a cron job:
 bash 
0 * * * * scp /var/www/tempr/tg*p.png username@mscroggs.co.uk:/path/to/folder
I hope this was vaguely interesting/useful. I'll try to add more details and updates over time. If you are building something similar, please let me know in the comments; I'd love to see what everyone else is up to.
Edit: Updated to reflect graphs now appearing on mscroggs.co.uk not catsindrag.co.uk.

Similar posts

How OEISbot works
Logic bot
Logical contradictions
Logic bot, pt. 2

Comments

Comments in green were written by me. Comments in blue were not written by me.
 Add a Comment 


I will only use your email address to reply to your comment (if a reply is needed).

Allowed HTML tags: <br> <a> <small> <b> <i> <s> <sup> <sub> <u> <spoiler> <ul> <ol> <li>
To prove you are not a spam bot, please type "s" then "e" then "g" then "m" then "e" then "n" then "t" in the box below (case sensitive):

Archive

Show me a random blog post
 2021 

Jan 2021

Christmas (2020) is over
 2020 
▼ show ▼
 2019 
▼ show ▼
 2018 
▼ show ▼
 2017 
▼ show ▼
 2016 
▼ show ▼
 2015 
▼ show ▼
 2014 
▼ show ▼
 2013 
▼ show ▼
 2012 
▼ show ▼

Tags

martin gardner hats tennis geogebra convergence quadrilaterals exponential growth pi arithmetic rugby national lottery palindromes matrix of cofactors curvature books computational complexity dragon curves triangles braiding pizza cutting royal baby manchester science festival error bars probability stickers approximation bodmas weather station chalkdust magazine trigonometry graphs finite element method sound speed games hannah fry final fantasy raspberry pi asteroids fractals signorini conditions draughts interpolation talking maths in public christmas christmas card video games boundary element methods frobel countdown pythagoras folding tube maps polynomials inline code advent calendar misleading statistics sobolev spaces data visualisation bempp captain scarlet folding paper electromagnetic field bubble bobble wave scattering reuleaux polygons phd european cup map projections big internet math-off ucl determinants reddit numerical analysis mathsteroids geometry coins rhombicuboctahedron twitter manchester gerry anderson data inverse matrices london underground simultaneous equations weak imposition matrices sorting craft machine learning platonic solids javascript flexagons game show probability mathsjam a gamut of games logs dates game of life nine men's morris gaussian elimination statistics football radio 4 oeis golden spiral royal institution matrix of minors accuracy php cambridge tmip chebyshev plastic ratio ternary squares python golden ratio programming the aperiodical pac-man cross stitch matrix multiplication logic london harriss spiral menace wool binary realhats hexapawn sport noughts and crosses people maths estimation light matt parker propositional calculus go puzzles world cup news latex dataset preconditioning pi approximation day mathslogicbot graph theory chess

Archive

Show me a random blog post
▼ show ▼
© Matthew Scroggs 2012–2021