The end draws near

Today, it's a bit harder to summarise exactly what I've learnt as it consisted of the material from 2 hours of lectures on machine learning and about an hour on language processing. I also learnt about how == works in Java between Strings and objects compared with primitive types. It might be a slow process, but hopefully I'm improving.

I feel a mixture of sadness and relief today as I've finished the second of the three free Stanford courses running this term. It's been interesting looking behind the scenes at how machine learning is being used all around us from news sites recommending news we might be interested in to variable pricing on websites depending on acceptance or rejection of previous offers to predicting whether a tumour might be cancer or not. The course was quite mathematical and the programming involved a high level of vectorisation so that built in algebra libraries could be used. Today I finally understood why we used the summation sign rather than just working with the vectorised version all the time. It's because in order to split the work over multiple computers or cores, we give each computer/core part of the summation to do, then combine the results.

It's really quite amazing what can be done, and is being done in this field. The course has given me quite a few "so that's how they do it" moments.

The course runs again from January for about 10 weeks. For details see http://jan2012.ml-class.org/. From looking at the other course dates, my guess is it will start around the last week in January.

Three things for today

1. Today I learnt that not only can you use compression to determine the language of a passage, but you can also use it to tell which of a series of photographs is the sharpest. A blurry image will compress more than a sharp one.
2. In java, StringBuilder can be used instead of, and if preferable to StringBuffer if not using multiple threads.
3. We have brains, first and foremost to control movement. There is a creature called a sea quirt which as a juvenille swims around but then finds a place to anchor itself. Once it has done this, it digests its own brain and nervous system for food. A brain isn't needed when you're not going to move.

Photo Wikipedia Commons: Nhobgood

For an interesting talk on the complexity of movement, and the purpose of the brain see the following TED talk.

Gzip and Determining Language

While watching the last set of videos for the free Stanford Artificial Intelligence course, the following video completely blew me out of the water. It was so completely unexpected.

This is my third thing I learnt on Monday. The unix command gzip can be used to recognise which language a passage is written in. Suppose you have passages in different languages, and want to know which language a new passage is written in. What you can do is concatenate the passage onto each of the other passages, compress and check which one has compressed the best. The reason this method works is because compression works by shortening the representation of common language patterns, such as "is " in English, by a single byte. This compression will be different for each language and thus the best compression should be achieved for the concatenation with the same language.

Finding Components in a Directed Graph

The second thing I've learnt today is about finding strongly connected components in a directed graph. A strongly connected component is one in which there exists a directed path between every pair of vertices in each direction.

The algorithm in involves starting with an ordering (any ordering) of the vertices, running a depth first search on the graph with all arcs reversed, while keeping note of position the vertices are removed from the stack. This position is then used to order the vertices in the original graph. A second depth first search is run, this time on the original graph with the new ordering of the vertices from largest to smallest. Whichever vertices are generated from the same leader are in the same component.

Example

For the directed graph above, I'll run through the algorithm. First we reverse all the arcs like this:

Starting at 1, we do a depth first search on the graph. From 1 we can go to 2 or 4, and we arbitarily pick 4. From 4 we can go to 10 or 6 so we'll go for 10. From 10 we have no choice but to go to 7, then 8 and from there to 9 and then 3. From 3 we have no unvisited vertex to add so 3 pops off the stack and gets new label 1. I'll use f(3)=1 to denote the new label of vertex 3.

1-> 4 -> 10 ->7-> 8->9->3 dead end so f(3)=1.
1->4->10->7->8->9 dead end so 9 pops off next giving vertex 9 the new label 2, that is, f(9)=2.
1->4->10->7->8 dead end so 8 pops off giving f(8)=3.
1->4->10->7 dead end so 7 pops off giving f(7)=4.
1->4->10 dead end so 10 pops off giving f(10)=5.
1->4    this time it isn't a dead end so we take the other option at 4 which is 6, then 5.
1->4->6 ->5  dead end since 1 has already been visited so 5 pops off giving f(5)=6.
1->4->6  dead end so f(6)=7.
1->4 dead end so f(4)=8.
1  not a dead end as we haven't yet visited 2.
1->2 but since 10 has already been visited this is a dead end. Thus f(2)=9.
1 dead end and finally 1 pops off giving f(1)=10.
Since all vertices have been visited, we're done with the first DFS. The original graph with the new ordering of vertices is shown below.

Starting at 10, we do a depth first search again, taking note of the leader vertex for each vertex, that is, the vertex which starts the path containing that vertex.

10-> 6->7->8.  Now  8 pops off then 7 then 6 and finally 10. All of these have leader vertex 10 and thus are in the same strongly connected component as 10.
The next unvisited vertex is 9, so we start the next path with 9. There is no unvisited vertex accessible from 9 so it's in a component on its own.
Now we move on to 5.
5->1->2->3->4.  Each of these vertices pops off, 4 then 3, 2, 1, 5. All of them have lead vertex 5 so are in the same strongly connected component..

All vertices have been visited so we are done with the second DFS. This leaves us with the following three components. Note that vertex 9 is in a component on its own and not the same component as 1,2,3,4,5.

Source
CS 161 - Design and Analysis of Algorithms Lectures 6

Kaprekar's Constant

I've been watching the University of Nottingham videos by Brady Haran on physics and chemistry for a while now but I hadn't come across this channel, numberphile before which is, rather unsurprisingly, about numbers.

So for the first thing I've learnt today, it's Kaprekar's constant. Take any four digit number, excluding numbers where all the digits are the same (0000, 1111, 2222, etc). Make the largest number and the smallest number out of these digits. Subtract them and repeat the process until it converges, that is you get the same number again. That number will always be 6174.

For example, take 2395. Rearrange the digits to make 9532 and 2359.
9532-2359 = 7173, and repeat
7731-1377 = 6354
6543-3456 = 3087
8730-0378 = 8352
8532-2358 = 6174
7641-1467 = 6174, and as we had this on the line above, we'll always get 6174 so the process has converged.

For more details, and an expansion to numbers with a different number of digits, see http://plus.maths.org/content/mysterious-number-6174.

It's been a while...

The last three months have been quite busy for me with three online courses to study. I've had a wonderful time learning lots of new things. When I started I thought I was going to struggle and not really be able to manage them. I've found that I could do more than I expected. I've found the three courses quite different.

Introduction to Databases

When I watched the first lecture on databases I thought I was crazy and didn't know what was going on. I had to pause and rewind the video multiple times. I felt completely in over my head. After a very shaky start, it became my favourite of the three courses. There were many additional exercises that meant I could really get my teeth into the material. I did everything. It brought back the joy and excitement of learning which made university such a wonderful time for me. I've missed the intellectual challenge.

Machine Learning

This was by far the most mathematical of the courses which meant that I could follow fairly easily. The programming exercises in Octave were frustrating at times as I seem to have a great ability to make the program crash. My poor laptop found it a little tough at times to process everything such as a load of spam emails to predict whether another one was spam or not. It's been great to see the sort of techniques used behind the scenes to analyse spam, categorise news or predict whether someone has a tumour or not.

Artificial Intelligence

This has been the most frustrating and yet most interesting course. I think if I'd watched the course from a casual point of view, I would have loved it. There have been hiccups over precision in asking questions which have lead to confusion. The lecturers are enthusiastic and you can really see how keen they are to explain their subject. It's a shame about the problems but the potential for a great course is there.

What's Next?

I'm trying to learn Java over Christmas so that I can take part in some more courses from January to April. A list of the available courses can be found at the bottom of this page: http://www.anatomy-class.org/. There are 16 courses at the moment, one of which is the machine learning course mentioned above. I don't know which ones I will do yet as they all sound interesting. I think I might just watch some of the courses without being active since I am sure my coding will not be good enough by then and it's also impossible for me to do 15 courses at once.

Java

So, in order to do these courses I've been working my way through http://codingbat.com/java which I'm finding quite helpful. It's a basic enough level that I can work quite quickly while learning some of the classes. I'll need to find something else later on to drag myself up to a higher level but I'll look for that later. I did start off with http://docs.oracle.com/javase/tutorial/java/TOC.html but it went too fast for me so I've paused that for a while and will come back to it later.

Regex

I've started reading one of the recommended books for Natural Language Processes and it looks like I need to get to grips with regular expressions. I've been intending learning this for several years so finally I'm going to do it.

Other Aims

I have quite a few other things I want to get done next year, and I've started to collect them together at a new site called Schemer. The following link is an invitation to the site: http://schemer.com/invite/9vidub2r7rqn6  (It's good for 20 invitations.) You can see other people's goals as well so there is lots of inspiration. Some of the things I'm hoping to do are

• become proficient at sewing - I have a sewing machine (well several) but I am not really confident in using it. I'd like to be able to alter clothes, make clothes and do patchwork on it.
• make a patchwork quilt
• finish some of the many half done projects I have
• learn some yoga
• learn three new things a day
• learn some more Dutch
• learn to recognise the constellations of the stars
• improve my knowledge of physics
• cook my way through a cookery book
• walk a few miles every week
• grow some vegetables

I'd rather have too many aims than too few - more chances to succeed! I don't know how I'm going to fit everything in but it going to be fun anyway.

1st October 2011 Things I Want to Accomplish This Month

These are my aims for October.

Dutch

I've been learning Dutch on and off for a couple of years, but not getting very far. Last month I came across a program memrise linked to by someone on Google+. I started using it at the beginning of September and since then I've learn about 500 words. I enjoy it and find it a fun way to learn the vocabulary without getting stressed or frustrated. Learning spellings in any language has always been something I'm quite bad at so this progress is quite significant for me.

This month I want to continue to work on those words, and further increase my vocabulary by at least 200 words.

Stanford Free Courses

I think I'm somewhat crazy to have signed up to all three of the Stanford free online courses for this autumn. They officially run from 10th October to 12 th December. The courses are

• http://www.db-class.org/ Introduction to Databases
• http://www.ml-class.org/ Machine Learning
• http://www.ai-class.com/ Artificial Intelligence

I've signed up for the basic track for AI and ML, but will be doing the full DB course. So far I've complete the first week of lectures and exercises for DB. It feels so good to be studying again in a structured way. I hope I will be able to allocate sufficient time to all of this as each is supposed to require approximately 10 hours per week. I'm not actually sure I have that much time but I will give it my best shot and I will know more than I would have if I had not attempted this.

Putting Together Ideas for 2012

A few years ago a friend of a friend decided to do 12 things, one per month over the course of the year. I tried it in a sort of messy, disorganised way and I accomplished some things but I didn't really have clear goals or really know what I wanted to do. It has been a positive experience, even though I didn't manage everything because it meant that I could look back over the year and say, "Yes, I did do something this year."

A couple of days ago, Christine Cantow Smith on Google+ posted a picture of a collage she is working on. When I saw it, I misread the word collage as college. Her collage contains lots of words and I thought, "Words, things to do at college, learning" and something clicked connecting it to the 12 things in a year.

What I'm going to do this month is collect together pictures and words connected to things I want to do and make a visual representation of what I want to do. I'm not sure whether it will turn out to be 12 things over the year, or some things spread out over a longer period. I'm swinging back and forth over that and over Yanik Falardeau's 30 changes in 30 days experiment which she carried out in August.

Exercise

I want to work exercise into my daily routine. I have EA sport active 2 which I set up today, so that is what I will be using, at least in part. I have leaves to clear in the garden and so I will use activities like that as well.

Craft

I would like to get at least two weeks ahead in my craft class preparation so that if I find I have too much to do with the courses, I have some flexibility.

Quests

I will continue to do the leaving the house quests. I am going to go to Cafe Scientifique on Tuesday for the first time. This time I will not have a preliminary test run to check I know where it is before hand, like I did with Skeptics in the Pub. I'm going to just find my way there somehow from looking at Google maps.

(*Added following section on 2011-10-02)

Clear Out

I have quite a lot of clothes and other things in the house that need to be thrown out. I'm going to try to do 15 minutes per day to make a dent in it.

29th September 2011 An Optimist's Tour of the Future

Last night I went to another Skeptics in the Pub talk. This talk should have occurred 6 weeks ago, but because of the riots, it was delayed which was good for me as I would have missed it otherwise.

It was a very different talk from the first one I went to on lucid dreaming which was packed full of so much information that my head was reeling afterwards. Who needs drugs when you can get an intellectual high from a talk like that? Whee!

The speaker was Mark Stevenson, and the title "An Optimist's Tour of the Future." It was about changing from looking at the future from a negative point of view to a 'Yes, there is a problem but there are also solutions.' The problem with the doom and gloom is that if we can't see hope, we just give up. What's the point of trying when we're going to fail anyway? Fear is a terrible motivator as it can also paralyse and cause us to give up.

Having a more optimistic view of the future isn't about denying there is a problem, but looking for solutions. Not the cynical 'No, can't solve that, impossible, wont work' but finding a vision and striving for it. There is no way I can express the hope the talk gave to me. The future could be better. It might not be, but that possibility, that glimmer of hope, exists and it's that we need to focus on and make happen.

Look how far we've come.

The amount of change over the last century has been incredible. Here are a few of the things that have been achieved, and are already being achieved.

Life Expectancy

The minimum life expectancy in any country in 1909 was 22 in Bangladesh. Now (2009 figures), the worst is in war torn Afghanistan at double that.

World Population and Food Production

Since 1950, even though the world population has increased from 2.6 billion to 6.9 billion (http://www.npg.org/facts/world_pop_year.htm), the per capita amount of food produced has also increased. There are two and a half times the number of people and we're producing more food per person? Remarkable. So why is there starvation? We've got the food but we're failing on the distribution.

The population is increasing but wont the world become full? The rate of increase of population is slowing and in some countries, the population is decreasing. ;A best guess estimate is that the world population will reach about 10 billion and then start to decrease. There is the capacity to feed that many people.
There's too much carbon dioxide. What can we do? There are materials being produced, and made into something that looks like a brush (http://knowledge.allianz.com/?1580/carbon-capture-artificial-trees-suck-co2-from-air) which captures carbon dioxide from the air and holds on to it. To release this carbon dioxide, just put the brush in water. Ok, so now we have a heap of carbon dioxide and what are we going to do with that? Make it into fuel! (http://www.brightgreencities.com/v1/en/bright-green-book/estados-unidos/conversao-direta-de-dioxide-de-carbon-e-agua-diretamente-em-combustivel/) The aim is carbon neutral fuel stations in 10 years.

Nanotechnology

Nanotechnology is enabling cheaper solutions - reducing the cost of desalination of sea water. How about something that looks like a teabag for less the 0.5 cents to filter water? (http://inhabitat.com/nanotech-tea-bag-purifies-drinking-water-for-less-than-a-penny/)

Agricultural Waste

Plants capture carbon, but then they die and rot and release it again. Turning agricultural waste into charcoal retains the captured carbon. Why would farmers do this? Two reasons.

• The right sort of charcoal can be used to improve the soil and increase yields by up to 50%. (The wrong sort can decrease it.) More carbon in the soil makes it retain more water, and the soil is more open so after a dry period, the rain doesn't just run off.
• It can be turned into a revenue stream, since agricultural waste can be turned into high quality activated carbon. Activated carbon is used in filtration systems.

Grazing Animals

In Australia, there are area where on one side of the fence the grass is overgrazed and the other it is long and dying. The growing part of grass is at the base, so if the base is blocked, then photosynthesis is restricted and the grass doesn't grow. When grass is eaten by animals, some of the roots are lost to the soil, which puts more carbon back into the soil. It's only a small amount, but a small amount repeated over and over leads to a large amount. (I don't know why this rotting doesn't release carbon dioxide into the atmosphere though.)

The usual way to farm is to split animals into smaller groups and have them in different fields, but this isn't how animals behave in nature. What do zebras do? They graze in tight groups for a few days in one area and then move on. Mimicking this by making fields into smaller sections, allowing the animals to graze for a couple of days and then moving them on leads to

• no need for fertilisers to make the grass grow
• increased biodiversity
• no need to buy food since the grass is growing

One farm in Australia using this method produces beef at a quarter of the Australian average leading to hugely increased profits.

Medicine

We have the skills to transplant organs, but there aren't enough donors. How can this be solved? Printing organs!


The video shows Luke, who had his bladder replaced by a new one grown in the lab 10 years ago.

Drugs

Many drugs are rejected because some people have negative reactions to them. What if the genomes of those people could be sequences and the gene causing the problem be isolated so that drug could be used for the ninety-nine people who could benefit from it and the one person who would have an adverse reaction could be given something else? Sequencing someone's genome is getting cheaper and cheaper, and it's claimed it can currently be done for $30.

At the moment about 1 in 5000 drugs are accepted for use so the drug companies have to absorb the cost of the others making the cost of drugs rocket. If  this cost did not have to be absorbed, then the cost of drugs could drop dramatically.

Barriers to Change

What is it that stops this exciting future from becoming a reality, and from problems being solved?

• Waiting for the government to act - governments are slow and if we wait for them to do something it will be too late. They need to see something being done so they can jump on the bandwagon.
• Cynicism. It's seen as cool and wise to be cynical but it blocks progress and is filled with negativity. It's bad for you and bad for the people around you. It's not about finding a way past problems, but just focusing on them. We need to take responsibility to keep our own cynicism in check.

Now what?

A few things

• The future is here already, it's just not evenly distributed. 
• If you can imagine a better future, you can aim for it.
• Keep cynicism in check.
• Never look at limitations as anything you ever comply with. (Cosmic speed limit? Let's wait and see.) 

For further information, the speaker has written a book, An Optimist's Tour of the Future which I haven't read yet. (I ordered it when I got home last night.) If it's half as good as the talk, it's going to be well worth reading. The book is going to be turned into a film, which is definitely something I want to see even though I dislike cinemas intensely.

Mark is also starting a "meeting place for people and organisations who want to make the world better". For further information see http://leagueofpragmaticoptimists.com/.

At the moment, I don't know what I can do except live with an attitude of hope and a vision of better things to come. That's a start, isn't it?

14th September 2011 Life as an RPG

Life as an RPG

A few weeks ago, I saw a t-shirt with the slogan "Achievement Unlocked: Left the House". Around the same time, I started to read posts by +Aristotle Bancale about life as an rpg. I love rpg, whether pen and paper adventures or computer games. I met my husband through a text based rpg, a MUD. Doing quests and levelling up in games is fun. I get it. I can do it. Dealing with real life - no, really not my thing. Was there something in the idea of making life into an rpg that could help me to deal with the anxiety of real life and dealing with new situations?

The Aim

I'd heard about meetings of skeptics in America, and wondered if there was anything similar in my area over here in the UK. I googled and found a local group. I thought that I'd like to go and meet some intelligent, thoughtful people in real life instead of just online. I wasn't particularly interested in the topic, but that didn't seem so important. I wanted to go to this meeting, but I was scared.

Quests and Achievements

So, how was I going to overcome the fear and panic and manage to do this? It started as just joking around about quests. Oh, do I get the 'Leave the house achievement for going to the doctors?' Yay! "How about the touring Europe quest since I've visited seven different countries?" "Let's make it level 2 for seven, with five countries for level 1."

The First Quest

Two weeks ago, a friend was visiting, and we went into Birmingham. Was I going to manage any quests? Could I find my way anywhere? I have no sense of direction at all, but with a lot of standing and looking around and thinking, I managed the "find my way to the bus stop from the market" quest. In the process of working out where I was, I drew a rough map to a shop I wanted to be able to find again. When I was doing this, with the thought of rpgs on my mind, I suddenly realised that I can't find my way in games either but I've developed a way of dealing with that. Why on earth was I not applying this to real life too? DOH!

Mapping the Route

A week later, it was time to try again, but this time going to the location of the meeting. The day before, I looked at google street view and travelled the route as I mapped it out in the same way as I map for games. Was this going to work?

The Second Quest

Saturday arrived, and my husband and I caught the bus into Birmingham. I started off, remembering the map but then I had to check it. One quick glance and I knew where I was going. I found the pub where the meeting would be held quite easily. It felt good! Going back to the bus stop? No problem. Finding the chocolate shop (with amazing 100% dark chocolate)? Easy peasy! The market? It's that way (pointing) but we'll go this way instead. That's four quests right there!

The Main Quest

So, tonight arrived. I was panicking. I wanted to go but I didn't want to go. I wasn't sure whether to just call it off but after dragging my husband into Birmingham on Saturday, it didn't seem fair not to try. I caught the bus to Birmingham. There was a girl and her friend sitting behind me on the bus and she wasn't feeling well. The poor lass was sick which took my mind completely off the meeting. I had some wet wipes and a plastic bag in my bag so was able to help out. I got off the bus with plenty of time to spare and wandered in the direction of the pub. I don't know what I was doing as I just turned right at a random place and walked on. After a minute or two, I thought, "Where on earth am I going?", turned around, went back the way I'd come and continued the right way.

Side Quest

Going home, I was going to need to catch the train. I hadn't practised this. The route to the pub passed the station so I thought I'd buy a ticket home so that if the talk finished late, I wouldn't have to mess around but could go straight to the train. What a silly station Birmingham New Street is. You go in the entrance, can get straight to the platform but there is nowhere to buy a ticket! Fortunately, I found someone to ask and was told I had to go down to the platform to get to the main part of the station. It certainly wasn't obvious where I was supposed to get a ticket but I found it and then went back the way I'd come. Now I knew how I was going to get home. Phew!

The Main Quest Continued

I was about half an hour early when I arrived at the pub. I find pubs rather daunting places so I didn't really want to go in. There were a couple of people outside so even though I really wanted to walk around the block and come back later, I thought I'd just look weird so I plunged in hoping to find the stairs down to where the meeting was. There were no stairs down. Utoh! I did a quick circuit of the room and dived into the ladies!

Now what should I do? I'm definitely in the right place, but which of these people are here for the meeting? No idea. I know, I'll buy a drink. That must be a quest. I know going to a pub was. I'm sure we talked about that one before. At least I'll have done some quests even if I don't stay for the meeting. When I got my drink, I asked where the meeting was. "Upstairs." I'm sure the notice said downstairs, but no matter.

I went upstairs to a room which was filling up rather quickly. I found a spot in the corner to perch and settled in. I was there. I'd done it! Achievement unlocked. Quest completed!

Conclusion

So did thinking of life as an rpg help? Most certainly. It gave me another perspective on how to do things. It enabled me to break down a problem into steps which were worth achieving on their own. It showed me how I could apply skills from gaming in everyday life. It felt empowering and I feel successful. I feel much more confident and able to do the next quest now, whatever that quest may be.

5th September 2011 Little Things Make a Difference: Just a Smile

About 3 weeks ago, as I was walking to a doctor's appointment, I smiled at a lady as I walked past and she smiled back. It brightened up my day and mood. It made a difference to me. It also set me thinking about how differently people interact on a day to day basis in a city compared with a day out in the countryside, and how different those two experiences feel.

When walking in the countryside, almost everyone makes eye contact with the people they meet on the way and exchanges a cheery good morning or afternoon. They may even stop for a chat. I love the sense of connection with others this gives, even though we will probably never meet again. It's good to take time to interact.

On the other hand, in the city, it's often hard to even get a smile from anyone. People rushing all the time with no time for connection, locked in their own private little worlds. Are we really too busy to smile?

I wonder how much less stressed and more connected we would feel if we just took a moment to smile at someone. Would other people would find their day brightened by that smile, or just find it weird? Maybe that person you smiled at lives alone and hasn't spoken to anyone all week. Would people feel threatened by the smile? Could it be a dangerous in some situations?

Link to discussion on G+.