It has been five months since I got my private pilot license! The winter wasn't offering many good days to go up and enjoy the freshness of the air. Finally, spring is here and unlike last year, it doesn't rain much this time. I haven't done much flying since last Nov (only two trips to Monterey?), and I couldn't wait to have a great (long) weekend to go further. This time, I go all the way south to see the closest airport to the beach -- Oceano, CA (L52).

When I work up and checked the weather this morning around 8:30 am, to my surprise, the fog covered the entire path from Palo Alto to Paso Robles. I could fly down the coast, but what if I cannot land in Oceano? I could only fly VFR (and I don't want to fly when I cannot see anything...I am not commuting. Seeing the landscape is part of the joy of flying by myself). I decided to wait a few hours, and it finally cleared up around 10am. Well, by the time I was in the air, it was already 12pm, but at least, I knew it would be clear all the way and remain clear for my night landing. I haven't done a night landing forever. The Marina layer that covers Bay Area is challenging.

On the way to Oceano, I flew inland most of the time. After Paso Robles, I decided to check out high way 58 and the Carrizo Plain National Monument area. It could be really pretty if the flowers are blooming. However, despite the hills were green, there was no visible trace of flowers in my sight. I headed directly to Oceano after that. Sorry to confuse traffic control (Oakland Center and Santa Barbara Approach...I guess I was on their boundary).

The entire flight was very smooth, until close to Oceano. I was wowing the beauty of the beach, the ocean, and the airport, then some turbulence called my attention back. Okay, I guess I need to control the airplane first and land safely...There's enough time to enjoy the beauty of the sight after I land.

Most of the time, after I land somewhere, I need to find a crew car (thanks Monterey!) or a rental car to get around. When I was planning for the flight last night, someone said that I wouldn't need a car in Oceano. Really? Aren't airports always far away from the towns? When I got close to the airport, yea, of course I won't need a car. When I was flying down wind, I was literally flying on top of the beach. I didn't expect it to be this close.

Because of the detour to the mountains, I ended up spending about 1.5+ hours for the entire flight, even with ~15 knots tailwind. Well, I was really hungry, so although I really wanted to see the beach, I decided to get some food first. After lunch, I finally had the energy to go for a long walk. On the maps, it said "Oceano Dunes SVRA". I was wondering, what's special about the beach? Soon I founded it out that people could drive their normal cars inside of the state park! That's just crazy.

After a two hours walk, I went back to my plane. Some flowers are already blooming, e.g. California poppy, though I am still waiting for the season to see them dominate the entire hill. California sunshine is always on the healing side. Just a little bit out of the bay (i.e. 1.5-hour flight), I can find so many beautiful places for a day adventure.

On the way back, I flew along the coast until Monterey, then directly to San Carlos. I was using autopilot all the way until I disengaged it near the silicon valley (where I had to manually control the plane). It was after sunset, and it took me 1.5 hours again due to headwind. Luckily, I could spare my hands and take some pictures. Traffic wasn't busy after sunset...NorCar approach was quiet with only some commercial airliners' traffic, and they flew IFR

Back to San Carlos, and then home. It's a long day but I was well rested mentally. One more achievement -- I remembered to open and close VFR flight plans both ways!

In the game, the player has to give gifts to all villagers to keep a good relationship with them. There is an official page displaying each one's preference, wiki. However, my life will be much easier if I can minimize the amount of distinct gifts I carry every day. When there is an optimization question, there is an analytical solution

My approach:

Use wiki's data as input, then identify the items that are favored by more than one villagers, and easy to obtain regardless of the season...as a result, I can arrange production and carriage easily and efficiently.

Output:

A network graph that shows how villagers are connected by gifts.

Source codes:

gift = read.csv("stardew valley gift.csv/Sheet 1-Table 1.csv", stringsAsFactors = F)

names(gift)

expand.gift = apply(gift, 1, 
      function (x) {
        gift_list = unlist(strsplit(x[2],"\n "))
        data.frame(v = x[1], g = gift_list)
        }
      )
expand.gift = do.call(rbind, expand.gift)

expand.gift$v = gsub("\n","",expand.gift$v)
expand.gift$g = gsub("[[:space:]]","",expand.gift$g)
expand.gift$v = paste0("v.",expand.gift$v)
names(expand.gift) = c("source","target")
write.csv(expand.gift, file = "expand.gift.csv", row.names = F)
expand.gift = subset(expand.gift, ! g %in% c("Prismatic Shard","Rabbit's Foot"))

expand.gift.mul = merge(expand.gift, expand.gift,
                        by.x = "v",by.y = "v")
expand.gift.mul = subset(expand.gift.mul, g.x!= g.y)

library(igraph)
gift.n = graph_from_edgelist(as.matrix(expand.gift.mul[,2:3]), T)
gift.n = as.undirected(gift.n, mode = "mutual")
V(gift.n)$size <- 1
l <- layout_with_kk(gift.n)
plot(gift.n,layout=l, vertex.label.cex	 = 0.7)

write_graph(gift.n, file = "svgift.gml",format = "gml")

Original dataset:
sheet-1-table-1.csv

Vector graph output:
svgift.pdf

The route was a loop starting from San Jose, then Monterey, then through 17 mile to Carmel, then down south to Big Sur and Hearst Castle, and finally drive back via 101.

We were fortune enough to see the fog disappears in 17 mile. Everything happened in a sudden; dynamic.

Then a front page photo of the famous tree in 17 mile.

We saw three happy (or scared) rabbits... near the concrete bridge.

Sharp cliff and sapphire blue sea.

Sunset Near the Hearst Castle.

Hope this helps my SEO (although it has been pretty good), as well as to keep everything consistent. Time to change my signature now

I went to the poetry room and found a seat in the corner. The room was very quite in the afternoon with a ray of sunshine coming in through the window. Everything was just perfect to have a seat and read. So I picked a book randomly and started to read. I was expecting to read a poetry book but it turned out that the book was actually about Afghanistan -- stories about Afghanistan behind a collection of lansays. The name of the book was I Am the Beggar of the World: Landays from Contemporary Afghanistan.

I was more interested in reading and feeling the stories. To be honest, I only had limited knowledge of the middle east (or the West Asia), in spite of a fortunate trip to Israel this summer. When thinking about Afghanistan, my reactions were the American-Taliban war, withdrawal of American armies from Afghanistan, and some pieces of memories on the sharp contrast of Afghanistan in 50 years ago v.s. today. The book records some real stories in Afghanistan -- sex, rape, slave, war, marriage, family, exchange, education. Some brutal stories happened simply because people had no other choice. A vivid example is women's roles in a family. In the early days, women were responsible for bringing drinkable water to the family, and at that time they used containers like jugs to carry water from rivers to their houses. Recently, some families started to dig deep well to extract water directly from the underground so women no longer had to go out and carry water back. The interesting part was that because of the risk of rape and kidnap, women were not allowed to go out if not necessary, then it became hard for young girls to meet young boys. As a result, young people had fewer chances to meet each other. This side effect makes it harder to judge whether that technology improvement was good or bad; however, the wide applications of Internet (e.g. facebook) have significantly and positively impacted people's lives, as this lansay shows.

Then marriage. In my generation, it is rarely the case that marriages are purely arranged by their families. Most people at least have the freedom to choose someone they do not hate though their families are still providing matching advice. In contrast, marriages in Afghanistan convey more economic meanings -- family links, exchanges, and simply reproduction. Males have irreplaceable roles in the war, and there are many widows and children left unavoidably. It is very hard to re-marry someone else, either in Afghanistan today or in China a century ago. People have to weigh economic factors more in uncertainty and poverty. A piece of lansay tells such story. A girl was arranged to marry a boy, but unfortunately the boy died during the war. According to the custom (or two families' agreement), the girl could either marry the boy's older brother or younger brother instead. However, both of them repelled the girl because the girl's father had no money to pay the dowry. Another lansay also reflects similar idea.

"When sisters sit together, they always praise their brothers.

When brothers sit together, they sell their sisters to others."

There are some remarkable statistics behind. During the Afghanistan Civil War (90s of last century), about 1/4 of the population (equivalent to 1.5M) fled to Pakistan, and thousands of women were raped on the way. There is a research paper saying that readers response more strongly to single pictures than numbers from massive statistics, and apparently we can tell how true it is from the way that media report Syrian refugees.

The name of the book comes from a poet in the book.

"In my dream, I am the president.

When I awake, I am the beggar of the world."

It tells a story of a married woman. In the day her husband has to go out to feed the family, and the woman stays at home like a beggar; at night, they could have some warm foods together and stay together in the bed. That's the only warm that leads to a good dream.

I also find this lansay touching.

I could have tasted death for a taste of your tongue

watching you eat ice cream when we were young.

Without the picture on the left I could not link this to my memories about the country from 50 years ago v.s. today. In the past, people lived a happy life with a lot of freedom and smiles; however, today they only have debris of the old city left. It reminds me of the past changes in China. In the past 30 years, China had significant improvements on all aspects and life qualities have always been increasing. It is very hard for me to imagine how it feels when everything is ruined and goes back to decades ago. In addition to Afghanistan, many other middle eastern countries have experienced similar transitions, say, Iraq, Syria, Egypt. I find myself speechless in front of the refugee topic. On one side, China is so far away from the Middle East, and China's role seems unique (from people's comments when I was in Israel, they hope China can mediate other political parties because there is less direct conflict of interest), and also there are almost no refugee coming to China to cause any issues. On the other side, even though I have lived in Europe and am living in the U.S. now, I am not from these areas and it is hard for me to think on behalf of the local people and understand their concerns. The only thing I can say is that, there is definitely no Pareto improvement to make all sides happy. It is impossible for the refugees to adapt to  European communities immediately and peacefully. I don't feel it is a unique issue caused by religions or ethic groups though. Certain conditions have to be satisfied to reach an equilibrium, and once there is an external shock, the equilibrium might be broken and hence we see some severe issues like sexual assaults in some European countries.

After all, it was nice to read a book and learn some real stories. It was also a precious opportunity for me to spend a whole afternoon reading a random book and thinking about life. I used to do it a lot when I was in Shanghai, but no so often since I moved to the bay area. However, my arty cells are woken up and it is time to enjoy the power of thinking.

2016.1.9 At City Lights and Brioche Bakery & Cafe, San Francisco.

$ python
Python 3.5.1 |Anaconda 2.4.1 (x86_64)| (default, Dec  7 2015, 11:24:55) 
[GCC 4.2.1 (Apple Inc. build 5577)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

Then I tried to start Rodeo, hmm, error message: "Bad news. Rodeo cannot start".

What can I do? I searched on the internet but found nothing. I can use both ipython and python from my terminal so I thought that could not be a problem. Then I made a guess - there must be something wrong with environment variables. I tried to echo my environment variables from the terminal:

$ echo $PATH
/Users/Liyun/anaconda/bin:/Users/Liyun/anaconda/bin:/usr/local/bin:/usr/bin:/bin:/usr/sbin:/sbin:/Library/TeX/texbin

It looks fine to me. Then I opened Rodeo again,  discarded the error message,  and opened its preference tab. Wait, I can specify the python I want to use here, and by default it is /user/bin/python! So I tried this python,

$ /usr/bin/python
Python 2.7.10 (default, Oct 23 2015, 18:05:06) 
[GCC 4.2.1 Compatible Apple LLVM 7.0.0 (clang-700.0.59.5)] on darwin
Type "help", "copyright", "credits" or "license" for more information.

Apparently, my macbook somehow comes with python 2.7. I changed the python path in Rodeo's preferences tab to /Users/Liyun/anaconda/bin/python and restarted Rodeo. This time it worked perfectly. Well, I guess for whatever reason Rodeo is trying to use the old python although I have installed Anaconda for it.

In nominal terms — the most appropriate measure when judging an economy’s global impact — India’s output is one-fifth that of China’s. India makes up a mere 2.5 per cent of global GDP against a hefty 13.5 per cent for China. If China grew at 5 per cent annually, it would add an Indian-sized economy to its already hefty output in less than four years. Saying India can match this is like saying a mouse can pull a tractor.

Then quickly checked China's GDP data...almost doubled since 6 years ago? (2009-2015). It is not just the math thing... not only add another India, China has already added another Japan-size economy. But wait, what does GDP mean for everyone?

That's like the question I had when I was wandering in streets in Tel Aviv...How should we account for economic growth? Especially for a big and quite unbalanced economy like China. My generation is not feeling stable -- so many people have to leave their hometowns to make a life either in Big Three (Beijing or Shanghai or Guangzhou/Shenzhen). Given another decade, how much worse could it even be?

Also wait... when US was at 10T China was not even 2T (2002)... now China/US is 10/17. Who can conclude that India cannot grow like China?

I think I am the kind of person who loves to travel alone. I seldom make a travel plan -- last time when I traveled to Tibet and Nepal I didn't even book a round-way ticket. That's the unpredictable part of traveling: I don't know what's going to happen, so everything is a surprise and I enjoy the process of discovery.

This time to Israel was in fact better organized. It was a business trip; otherwise it would be very hard for me to get a visa to Israel. I had to stay in office on workdays; but that was not too bad either, because I could chat with Israeli colleagues and learn from them. Of course weekends were my adventure time.

600 KM Drive

The most remarkable day was the second Friday (Sunday-Thursday are workdays in Israel), when I drove 600 km by myself up to the north. Haifa, Sea of Galilee, Golan Heights. I watched the most beautiful moon-rise in my life when the moon rose up from mountains over the Galilee Sea. I could not stop myself from constantly driving around Sea of Galilee until the sky went completely dark and my GPS kept correcting me to the right route back to Tel Aviv. It was too amazing to be rational. Time flew without awareness.

Moon rise at the Galilee Sea

When I walked to a Cafe on top of the Bahai Garden for a short afternoon tea, it turned out to be a coincidence that a painter was drawing a painting that very similar to me! I wish I was in a long light dress so I could have matched the painting much better!

Coincidence!

The painter and her painting.

Israeli People

Israeli people were also active, open and hospitable. My colleagues took me to stunning places every noon for lunch and underground bars for midnight parties. Even random people on the street were keen to chat with me. In Haifa, a young guy who was a Haifa native asked me if he could show me around his city and introduce its histories. He scared me when he asked if I wanted to stay in Haifa for that night and even I was willing to move to Israel and get married...I was shocked but the second day my colleagues told me that was normal. That was just the way how Jewish people expressed themselves. Similarly in Tel Aviv when I asked a group of energetic men to take a photo of me on the beach, they even asked me if I just wanted a photo of myself or a photo of both of us. I felt that people were just curious to meet an East-Asian girl.

The Jewish Culture

The Jewish culture was also my main interest during this trip. Fortunately I managed to pay a visit to the Beit Hatfutsot, Museum of the Jewish People. The museum recorded history of Jewish movements around the world: how they spread to other continents and how they finally made it back to Israel. The most impressive picture was when I saw a sculpture that demonstrated Jewish people's attitude towards education:

"The Jewish family put the child's education above everything".

Also unity sits in the heart of the Jews:

"All Jews are responsible for one another".

Jewish People and China

Jewish Synagogue in China from the 12th century.

They also had a synagogue (means church for Jewish people to get-together) in China from 1000 years ago. It happened to be the 70th Anniversary of World Anti-Fascist War and Israel consulate in Shanghai made a short video to thank Shanghai for refuge.

Sleepless Tel Aviv

Tel Aviv is 24 hours sleepless. We arrived on Sunday midnight (1am) and everything was open on the beach! Families and children were enjoying their times playing on the beach...Bars and restaurants were open to accommodate friends and parties.  One beef Carpaccio and a glass of cocktail...night life starts and never ends.

At my last night in Tel Aviv I ran into a musical concert in the Old Jaffa City. Vigorous band, devoted singer and amazed audiences when you sit in a historical open-air theater next to the Mediterranean Sea.

Music Concert in Old Jaffa City

Tel Aviv is also open to homosexuals. Although from the legal perspective gay marriage is not recognized officially yet, they can enjoy their lives anyway and easily in Tel Aviv. Look at their graffiti on the street.

Homosexual graffiti

The Caves

I also made a short trip to Beit Guvrin-Maresha National Park. The park is famous for big caves:

For thousands of years people have been cutting into the rock beneath the nari as quarries, burial caves, storerooms, industrial facilities, hideouts and dovecotes.

Some of the caves were huge and people actually lived inside -- very cool compared to the outside heat. A residential cave can consist of several rooms for different purposes: bedroom, storage, oil press etc.

Entrance to a cave

The Bell Cave

< to be continued?>

This content is password-protected. To view it, please enter the password below.

Password:

• Native close form solution: just . We can always solve that inverse matrix. It works fine for small dataset but to inverse a large matrix might be very computations expensive.
• QR decomposition: this is the default method in R when you run lm(). In short, QR decomposition is to decompose the X matrix to X = QR where Q is an orthogonal matrix and R is an upper triangular matrix. Therefore, and then then then . Because R is a upper triangular matrix then we can get beta directly after computing Q'Y. (More details)
• Regression anatomy formula: my boss mentioned it (thanks man! I never notice that) and I read the book Mostly Harmless Econometrics again today, on page 36 footnote, there is the regression anatomy formula. Basically if you have solved a regression already and just want to add an additional control variable, then you can follow this approach to make the computation easy.
  
  Especially if you have already computed a simple A/B test (i.e. only one dummy variable on the right hand side), then you can obtain such residues directly without running a real regression and then compute the estimate for your additional control variables straightforwardly. The variance estimate also follows.
• Bootstrap: in most case bootstrap is expensive because you need to re-draw repeatably from your sample. However, if it is a very large data and it is naturally distribution over a parallel file distribution system (e.g. Hadoop), then draw from each node could be the best map-reduce strategy you may adopt in this case. As far as I know, the rHadoop package accommodates such idea for their parallel lm() function (or map-reduce algorithm).

Any other ways?