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 "o" then "d" then "d" in the box below (case sensitive):

Archive

Show me a random blog post
 2019 

Sep 2019

A non-converging LaTeX document
TMiP 2019 treasure punt

Jul 2019

Big Internet Math-Off stickers 2019

Jun 2019

Proving a conjecture

Apr 2019

Harriss and other spirals

Mar 2019

realhats

Jan 2019

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

Tags

platonic solids chebyshev big internet math-off ternary golden spiral tennis hexapawn javascript cambridge pythagoras london underground manchester science festival coins stickers chess manchester folding paper raspberry pi menace games matt parker game of life go pac-man pizza cutting bubble bobble trigonometry asteroids a gamut of games craft php people maths sorting flexagons electromagnetic field graph theory machine learning london talking maths in public countdown realhats hats reddit martin gardner plastic ratio binary nine men's morris captain scarlet royal baby chalkdust magazine accuracy python european cup map projections sport reuleaux polygons polynomials estimation rhombicuboctahedron noughts and crosses arithmetic national lottery programming christmas inline code mathsjam statistics latex video games error bars dataset books tmip news wool cross stitch misleading statistics curvature geometry weather station triangles golden ratio palindromes christmas card speed gerry anderson draughts rugby propositional calculus world cup radio 4 light dates mathslogicbot approximation logic probability twitter bodmas football final fantasy the aperiodical interpolation braiding frobel dragon curves puzzles mathsteroids game show probability sound oeis harriss spiral folding tube maps data fractals

Archive

Show me a random blog post
▼ show ▼
© Matthew Scroggs 2019