mscroggs.co.uk
mscroggs.co.uk

subscribe

Blog

Archive

Show me a Random Blog Post
 2017 
 2016 
 2015 
 2014 
 2013 
 2012 

Tags

folding paper folding tube maps london underground platonic solids london rhombicuboctahedron raspberry pi weather station programming python php inline code news royal baby probability game show probability christmas flexagons frobel coins reuleaux polygons countdown football world cup sport stickers tennis braiding craft wool emf camp people maths trigonometry logic propositional calculus twitter mathslogicbot oeis pac-man graph theory video games games chalkdust magazine menace machine learning javascript martin gardner reddit national lottery rugby puzzles advent game of life dragon curves fractals pythagoras geometry triangles european cup dates palindromes chalkdust christmas card bubble bobble asteroids final fantasy curvature binary arithmetic bodmas statistics error bars estimation accuracy misleading statistics pizza cutting captain scarlet gerry anderson light sound speed

Archive

Show me a Random Blog Post
▼ show ▼
 2015-08-29 

How OEISbot Works

A few weeks ago, I made OEISbot, a Reddit bot which posts information whenever an OEIS sequence is mentioned.
This post explains how OEISbot works. The full code can be found on GitHub.

Getting Started

OEISbot is made in Python using PRAW (Python Reddit Api Wrapper). PRAW can be installed with:
 bash 
pip install praw
Before making a bot, you will need to make a Reddit account for your bot, create a Reddit app and obtain API keys. This python script can be used to obtain the necessary keys.
Once you have your API keys saved in your praw.ini file, you are ready to make a bot.

Writing the Bot

First, the necessary imports are made, and test mode is activated if the script is run with test as an argument. We also define an exception that will be used later to kill the script once it makes a comment.
 python 
import praw
import re
import urllib
import json
from praw.objects import MoreComments

import sys
test = False
if len(sys.argv) > 1 and sys.argv[1] == "test":
    test = True
    print("TEST MODE")

class FoundOne(BaseException):
    pass

To prevent OEISbot from posting multiple links to the same sequence in a thread, lists of sequences linked to in each thread can be loaded and saved using the following functions.
 python 
def save_list(seen, _id):
    print(seen)
    with open("/home/pi/OEISbot/seen/"+_id, "w"as f:
        return json.dump(seen, f)

def open_list(_id):
    try:
        with open("/home/pi/OEISbot/seen/" + _id) as f:
            return json.load(f)
    except:
        return []
The following function will search a post for a mention of an OEIS sequence number.
 python 
def look_for_A(id_, text, url, comment):
    seen = open_list(id_)
    re_s = re.findall("A([0-9]{6})", text)
    re_s += re.findall("oeis\.org/A([0-9]{6})", url)
    if test:
        print(re_s)
    post_me = []
    for seq_n in re_s:
        if seq_n not in seen:
            post_me.append(markup(seq_n))
            seen.append(seq_n)
    if len(post_me) > 0:
        post_me.append(me())
        comment(joiner().join(post_me))
        save_list(seen, id_)
        raise FoundOne
The following function will search a post for a comma-separated list of numbers, then search for it on the OEIS. If there are 14 sequences or less found, it will reply. If it finds a list with no matches on the OEIS, it will message /u/PeteOK, as he likes hearing about possibly new sequences.
 python 
def look_for_ls(id_, text, comment, link, message):
    seen = open_list(id_)
    if test:
        print(text)
    re_s = re.findall("([0-9]+\, *(?:[0-9]+\, *)+[0-9]+)", text)
    if len(re_s) > 0:
        for terms in ["".join(i.split(" ")) for i in re_s]:
            if test:
                print(terms)
            if terms not in seen:
                seen.append(terms)
                first10, total = load_search(terms)
                if test:
                    print(first10)
                if len(first10)>and total <= 14:
                    if total == 1:
                        intro = "Your sequence (" + terms \
                            + ") looks like the following OEIS sequence."
                    else:
                        intro = "Your sequence (" + terms + \
                            + ") may be one of the following OEIS sequences."
                    if total > 4:
                        intro += " Or, it may be one of the " + str(total-4) \
                            + " other sequences listed [here]" \
                            "(http://oeis.org/search?q=" + terms + ")."
                    post_me = [intro]
                    if test:
                        print(first10)
                    for seq_n in first10[:4]:
                        post_me.append(markup(seq_n))
                        seen.append(seq_n)
                    post_me.append(me())
                    comment(joiner().join(post_me))
                    save_list(seen, id_)
                    raise FoundOne
                elif len(first10) == 0:
                    post_me = ["I couldn't find your sequence (" + terms \
                        + ") in the [OEIS](http://oeis.org). "
                        "You should add it!"]
                    message("PeteOK",
                            "Sequence not in OEIS",
                            "Hi Peter, I've just found a new sequence (" \
                            + terms + ") in [this thread](link). " \
                            "Please shout at /u/mscroggs to turn the " \
                            "feature off if its spamming you!")
                    post_me.append(me())
                    comment(joiner().join(post_me))
                    save_list(seen, id_)
                    raise FoundOne

def load_search(terms):
    src = urllib.urlopen("http://oeis.org/search?fmt=data&q="+terms).read()
    ls = re.findall("href=(?:'|\")/A([0-9]{6})(?:'|\")", src)
    try:
        tot = int(re.findall("of ([0-9]+) results found", src)[0])
    except:
        tot = 0
    return ls, tot
The markup function loads the necessary information from OEIS and formats it. Each comment will end with the output of the me function. The ouput of joiner will be used between sequences which are mentioned.
 python 
def markup(seq_n):
    pattern = re.compile("%N (.*?)<", re.DOTALL|re.M)
    desc = urllib.urlopen("http://oeis.org/A" + seq_n + "/internal").read()
    desc = pattern.findall(desc)[0].strip("\n")
    pattern = re.compile("%S (.*?)<", re.DOTALL|re.M)
    seq = urllib.urlopen("http://oeis.org/A" + seq_n + "/internal").read()
    seq = pattern.findall(seq)[0].strip("\n")
    new_com = "[A" + seq_n + "](http://oeis.org/A" + seq_n + "/): "
    new_com += desc + "\n\n"
    new_com += seq + "..."
    return new_com

def me():
    return "I am OEISbot. I was programmed by /u/mscroggs. " \
           "[How I work](http://mscroggs.co.uk/blog/20). " \
           "You can test me and suggest new features at /r/TestingOEISbot/."

def joiner():
    return "\n\n- - - -\n\n"
Next, OEISbot logs into Reddit.
 python 
= praw.Reddit("OEIS link and description poster by /u/mscroggs.")

access_i = r.refresh_access_information(refresh_token=r.refresh_token)
r.set_access_credentials(**access_i)

auth = r.get_me()
The subs which OEISbot will search through are listed. I have used all the math(s) subs which I know about, as these will be the ones mentioning sequences.
 python 
subs = ["TestingOEISbot","math","mathpuzzles","casualmath","theydidthemath",
        "learnmath","mathbooks","cheatatmathhomework","matheducation",
        "puremathematics","mathpics","mathriddles","askmath",
        "recreationalmath","OEIS","mathclubs","maths"]
if test:
    subs = ["TestingOEISbot"]
For each sub OEISbot is monitoring, the hottest 10 posts are searched through for mentions of sequences. If a mention is found, a reply is generated and posted, then the FoundOne exception will be raised to end the code.
 python 
try:
    for sub in subs:
        print(sub)
        subreddit = r.get_subreddit(sub)
        for submission in subreddit.get_hot(limit = 10):
            if test:
                print(submission.title)
            look_for_A(submission.id,
                       submission.title + "|" + submission.selftext,
                       submission.url,
                       submission.add_comment)
            look_for_ls(submission.id,
                        submission.title + "|" + submission.selftext,
                        submission.add_comment,
                        submission.url,
                        r.send_message)

            flat_comments = praw.helpers.flatten_tree(submission.comments)
            for comment in flat_comments:
                if ( not isinstance(comment, MoreComments)
                     and comment.author is not None
                     and comment.author.name != "OEISbot" ):
                    look_for_A(submission.id,
                               re.sub("\[[^\]]*\]\([^\)*]\)","",comment.body),
                               comment.body,
                               comment.reply)
                    look_for_ls(submission.id,
                                re.sub("\[[^\]]*\]\([^\)*]\)","",comment.body),
                                comment.reply,
                                submission.url,
                                r.send_message)

except FoundOne:
    pass

Running the Code

I put this script on a Raspberry Pi which runs it every 10 minutes (to prevent OEISbot from getting refusals for posting too often). This is achieved with a cron job.
 bash 
*/10 * * * * python /path/to/bot.py

Making Your Own Bot

The full OEISbot code is available on GitHub. Feel free to use it as a starting point to make your own bot! If your bot is successful, let me know about it in the comments below or on Twitter.
Edit: Updated to describe the latest version of OEISbot.

Similar Posts

Logic Bot
Raspberry Pi Weather Station
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).

To prove you are not a spam bot, please type "goo" in the box below (case sensitive):
 2014-11-26 

Logic Bot

Last week, mathslogicbot started the long task of tweeting every tautology in propositional calculus. This post explains what this means and how I did it.

What is Propositional Calculus?

Propositional calculus is a form of mathematical logic, in which the formulae (the logical 'sentences') are made up of the following symbols:

Formulae

Formulae are defined recursively using the following rules:
For example, \((a\vee b)\), \(\neg f\) and \(((a\vee b)\rightarrow\neg f)\) are formulae.
Each of the variables is assigned a value of either "true" or "false", which leads to each formula being either true or false:

Tautologies

A tautology is a formula that is true for any assigment of truth values to the variables. For example:
\((a\vee \neg a)\) is a tautology because: if \(a\) is true then \(a\) or \(\neg a\) is true; and if \(a\) is false, then \(\neg a\) is true, so \(a\) or \(\neg a\) is true.
\((a\leftrightarrow a)\) is a tautology because: if \(a\) is true then \(a\) and \(a\) are both true; and if \(a\) is false then \(a\) and \(a\) are both false.
\((a\wedge b)\) is not a tautology because if \(a\) is true and \(b\) is false, then it is false.
The following are a few more tautologies. Can you explain why they are always true?

Python

If you want to play with the Logic Bot code, you can download it here.
In order to find all tautologies less than 140 characters long, one method is to first generate all formulae less than 140 characters then check to see if they are tautologies. (This is almost certainly not the fastest way to do this, but as long as it generates tautolgies faster than I want to tweet them, it doesn't matter how fast it runs.) I am doing this on a Raspberry Pi using Python in the following way.

All Formulae

The following code is writing all the formulae that are less than 140 characters to a file called formulae.
 python 
from os.path import join
path = "/home/pi/logic"
First import any modules needed and set the path where the file will be saved.
 python 
def candidate(formula):
    global formulae

    if len(formula) <= 140 and formula not in formulae:
        formulae.append(formula)
        print formula
        f = open(join(path,"formulae"),"a")
        f.write(formula + "\n")
        f.close()
This function checks that a formula is not already in my list of formulae and shorter than 140 characters, then adds it to the list and writes it into the file.
 python 
variables = ["a""b""c""d""e""f""g""h""i""j",
             "k""l""m""n""o""p""q""r""s""t",
             "u""v""w""x""y""z""@""#""2""3",
             "4""5""6""7""8""9"]
This line says which characters are going to be used as variables. It is impossible to write a formula in less that 140 characters with more than 36 different variables so these will be sufficient. I haven't used 0 and 1 as these are used to represent false and true later.
 python 
= open(join(path,"formulae"))
formulae = f.readlines()
for i in range(0,len(formulae)):
    formulae[i] = formulae[i].strip("\n")
f.close()
These lines load the formulae already found from the file. This is needed if I have to stop the code then want to continue.
 python 
oldlen = 0
newlen = 26

while oldlen != newlen:
    for f in formulae + variables:
        candidate("-" + f)
    for f in formulae + variables:
        for g in formulae:
            for star in ["I""F""N""U"]:
                candidate("(" + f + star + g + ")")
    oldlen = newlen
    newlen = len(formulae)
The code inside the while loop goes through every formula already found and puts "-" in front of it, then takes every pair of formulae already found and puts "I", "F", "N" or "U" between them. These characters are used instead of the logical symbols as using the unicode characters leads to numerous python errors. The candidate function as defined above then adds them to the list (if they are suitable). This continues until the loop does not make the list of formulae longer as this will occur when all formulae are found.
 python 
= open(join(path,"formulae"),"a")
f.write("#FINISHED#")
f.close()
Once the loop has finished this will add the string "#FINISHED#" to the file. This will tell the truth-checking code when the it has checked all the formulae (opposed to having checked all those generated so far).

Tautologies

Now that the above code is finding all formulae, I need to test which of these are tautologies. This can be done by checking whether every assignment of truth values to the variables will lead to the statement being true.
 python 
from os.path import join
path = "/home/pi/logic"
First import any modules needed and set the path where the file will be saved.
 python 
def next(ar,i=0):
    global cont
    if i < len(ar):
        if ar[i] == "0":
            ar[i] = "1"
        else:
            ar[i] = "0"
            ar = next(ar, i + 1)
    else:
        cont = False
    return ar
Given an assignment of truth values, this function will return the next assignment, setting cont to False if all the assignments have been tried.
 python 
def solve(lo):
    lo = lo.replace("-0""1")
    lo = lo.replace("-1""0")

    lo = lo.replace("(0I0)""1")
    lo = lo.replace("(0I1)""1")
    lo = lo.replace("(1I0)""0")
    lo = lo.replace("(1I1)""1")

    lo = lo.replace("(0F0)""1")
    lo = lo.replace("(0F1)""0")
    lo = lo.replace("(1F0)""0")
    lo = lo.replace("(1F1)""1")

    lo = lo.replace("(0N0)""0")
    lo = lo.replace("(0N1)""0")
    lo = lo.replace("(1N0)""0")
    lo = lo.replace("(1N1)""1")

    lo = lo.replace("(0U0)""0")
    lo = lo.replace("(0U1)""1")
    lo = lo.replace("(1U0)""1")
    lo = lo.replace("(1U1)""1")

    return lo
This function will replace all instances of "NOT TRUE" with "FALSE" and so on. It will be called repeatedly until a formula is reduced to true or false.
 python 
= open(join(path,"formulae"))
formulae = f.readlines()
f.close()

= open(join(path,"donet"))
= int(f.read())
f.close()

variables = ["a""b""c""d""e""f""g""h""i""j",
             "k""l""m""n""o""p""q""r""s""t",
             "u""v""w""x""y""z""@""#""2""3",
             "4""5""6""7""8""9"]
These lines read the formulae from the file they are saved in and load how many have been checked if this script has been restarted. The the variables are set.
 python 
while formulae[-1] != "#FINISHED#" or i < len(formulae) - 1:
    if i < len(formulae):
        formula = formulae[i].strip("\n")
These lines will loop through all formulae until "#FINISHED#" is reached.
 python 
        insofar = True
        inA = []
        fail = False
        for a in variables:
            if a not in formula:
                insofar = False
            elif not insofar:
                fail = True
                break
            else:
                inA.append(a)
Here, the code checks that if a variable is in the formula, then all the previous variables are in the formula. This will prevent the Twitter bot from repeating many tautologies that are the same except for the variable a being replaced by b (although there will still be some repeats like this. Can you work out what these will be?).
 python 
        if not fail:
            valA = ["0"]*len(inA)
            cont = True
            taut = True
            while cont and taut:
                feval = formula
                for j in range(0,len(inA)):
                    feval = feval.replace(inA[j],valA[j])
                while feval not in ["0""1"]:
                    feval = solve(feval)
                if feval != "1":
                    taut = False
                valA = next(valA)
            if taut:
                f = open(join(path,"true"),"a")
                f.write(str(formula) + "\n")
                f.close()
    
        i += 1
        f = open(join(path,"donet"),"w")
        f.write(str(i))
        f.close()
Now, the formula is tested to see if it is true for every assignment of truth values. If it is, it is added to the file containing tautologies. Then the number of formulae that have been checked is written to a file (in case the script is stopped then resumed).
 python 
    else:
        f = open(join(path,"formulae"))
        formulae = f.readlines()
        f.close()
If the end of the formulae file is reached, then the file is re-loaded to include all the formulae found while this code was running.

Tweeting

Finally, I wrote a code that tweets the next item in the file full of tautologies every three hours (after replacing the characters with the correct unicode characters).

How Long Will it Take?

Now that the bot is running, it is natural to ask how long it will take to tweet all the tautologies.
While it is possible to calculate the number of formulae with 140 characters or less, there is no way to predict how many of these will be tautologies without checking. However, the bot currently has over 13 years of tweets lines up. And all the tautologies so far are under 30 characters so there are a lot more to come...
Edit: Updated time left to tweet.

Similar Posts

Logical Contradictions
Logic Bot, pt. 2
How OEISbot Works
Raspberry Pi Weather Station

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).

To prove you are not a spam bot, please type "very" in the box below (case sensitive):
 2013-07-11 

Raspberry Pi Weather Station

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).

To prove you are not a spam bot, please type "oak" in the box below (case sensitive):
© Matthew Scroggs 2017