Over the couple of months there have been a bunch of smaller releases to packages in the tidyverse . This includes: forcats 0.2.0, for working with factors. readr 1.1.0, for reading flat-files from disk. stringr 1.2.0, for manipulating strings. tibble 1.3.0, a modern re-imagining of the data frame. This blog post summarises the most important new features, and points to the full release notes where you can learn more. (If you’ve never heard of the tidyverse before, it’s an set of packages that are designed to work together to help you do data science. The best place to learn all about it is R for Data Science .) forcats 0.2.0 forcats has three new functions: as_factor() is a generic version of as.factor(), which creates factors from character vectors ordered by appearance, rather than alphabetically. This ensures means that as_factor(x) will always return the same result, regardless of the current locale. fct_other() makes it easier to convert selected levels to “other”: See the full list of other changes in the release notes . stringr 1.2.0 This release includes a change to the API: str_match_all() now returns NA if an optional group doesn’t match (previously it returned “”). This is more consistent with str_match() and other match failures. There are three new features: In str_replace(), replacement can now be a function. The function is once for each match and its return value will be used as the replacement. New str_which() mimics grep() A new vignette ( vignette("regular-expressions") ) describes the details of the regular expressions supported by stringr. The main vignette ( vignette("stringr") ) has been updated to give a high-level overview of the package. See the full list of other changes in the release notes . readr 1.1.0 readr gains two new features: All write_*() functions now support connections. This means that that you can write directly to compressed formats such as .gz, bz2 or .xz (and readr will automatically do so if you use one of those suffixes). write_csv ( iris , "iris.csv.bz2" ) parse_factor(levels = NULL) and col_factor(levels = NULL) will produce a factor column based on the levels in the data, mimicing factor parsing in base R (with the exception that levels are created in the order seen). See the full list of other changes in the release notes . tibble 1.3.0 tibble has one handy new function: deframe() is the opposite of enframe(): it turns a two-column data frame into a named vector. df - tibble ( x = c ( "a" , "b" , "c" ) , y = 1 : 3 ) deframe ( df ) # a b c # 1 2 3
八、因果推理法常用句型 1.Because/Since we read the book, we have learned a lot. 2.If we read the book, we would learn a lot. 3.We read the book; as a result / therefore / thus / hence / consequently / for this reason / because of this, we've learned a lot. 4.As a result of /Because of/Due to/Owing to reading the book, we've learned a lot. 由于阅读这本书，我们已经学到了很多。 5.The cause of/reason for/overweight is eating too much. 6.Overweight is caused by/due to/because of eating too much. 7.The effect/consequence/result of eating too much is overweight. 8.Eating too much causes/results in/leads to overweight. 吃太多导致超重。
http://www.bbc.com/news/magazine-21969100 How much gold is there in the world? By Ed Prior BBC News Continue reading the main story In today's Magazine Gunther, Christine and Otto Should high schools play American football? The battle to make Tommy the chimp a person The boy who grew up to be a suicide bomber Imagine if you were a super-villain who had taken control of all the world's gold, and had decided to melt it down to make a cube. How long would the sides be? Hundreds of metres, thousands even? Actually, it's unlikely to be anything like that size. Warren Buffett, one of the world's richest investors, says the total amount of gold in the world - the gold above ground, that is - could fit into a cube with sides of just 20m (67ft). But is that all there is? And if so, how do we know? A figure that is widely used by investors comes from Thomson Reuters GFMS, which produces an annual gold survey. Their latest figure for all the gold in the world is 171,300 tonnes - which is almost exactly the same as the amount in our super-villain's imaginary cube. A cube made of 171,300 tonnes would be about 20.7m (68ft) on each side. Or to put it another way, it would reach to 9.8m above ground level if exactly covering Wimbledon Centre Court. But not everyone agrees with the GFMS figures. Estimates range from 155,244 tonnes, marginally less than the GFMS figure, to about 16 times that amount - 2.5 million tonnes. That bigger figure would make a cube of sides 50m (166ft) long, or a column of gold towering 143m above Wimbledon centre court. So why are the figures so different? Part of the reason is that gold has been mined for a very long time - more than 6,000 years, according to gold historian Timothy Green. Continue reading the main story “ Start Quote All the gold that has been mined throughout history is still in existence ” James Turk Gold Money The first gold coins were minted in about 550 BC under King Croesus of Lydia - a province in modern-day Turkey - and quickly became accepted payment for merchants and mercenary soldiers around the Mediterranean. Up until 1492, the year Columbus sailed to America, GFMS estimates that 12,780 tonnes had been extracted. But one investor who looked at the research done in this area, James Turk, the founder of Gold Money, discovered what he regarded as a series of over-estimates . He believes that the primitive mining techniques used up to the Middle Ages mean that this figure is much too high, and that a more realistic total is just 297 tonnes. Tonnes of gold GFMS James Turk Pre-1492 12,780 297 Post-1492 158520 154947 Total 171,300 155,244 His figure for the overall amount of gold in the world is 155,244 tonnes - 16,056 tonnes, or 10% less, than the assessment by Thompson Reuters GFMS. A relatively small disparity, perhaps, but one that at today's prices comes to more than $950bn. His conclusions are accepted by some investors but such is the feeling between rival analysts that one competitor described Turk's figures as an alternative to the GFMS's "in the same way that Jedi is an alternative to Christianity". But there are others who think both sets of figures are too low. "In Tutankhamen's tomb alone they found that his coffin was made from 1.5 tonnes of gold, so imagine the gold that was found in the other tombs that were ransacked before records were taken of them," says Jan Skoyles of gold investment firm The Real Asset Company. While James Turk makes only minor adjustments to the GFMS figure for the amount of gold mined after 1492, Skoyles points out that even today China is "not particularly open" about how much gold it is mining. And in some countries, such as Colombia, "there's a lot of illegal mining going on", she says. She doesn't have an exact figure to offer, but one organisation that has tried to do some maths is the Gold Standard Institute. There is much gold still in the ground, like here in Democratic Republic of Congo Its experts believe that if we emptied our bank vaults and jewellery boxes, we'd find no less than 2.5 million tonnes of gold - though they admit that the evidence is somewhat sparse and the figure is a bit speculative. Continue reading the main story More or Less: Behind the stats Listen to More or Less on BBC Radio 4 and the World Service, or download the free podcast Download the More or Less podcast More stories from More or Less So who's right? Well, we don't know. In the end, all these numbers are made up of estimates added to estimates added to yet more estimates. Maybe they're all way off. The good news is that we are not likely to run out of gold any time soon. The US Geological Survey estimates there are 52,000 tonnes of minable gold still in the ground and more is likely to be discovered. The bad news is that the way we use gold is starting to change. Up to now it has never gone away. It has always been recycled. "All the gold that has been mined throughout history is still in existence in the above-ground stock. That means that if you have a gold watch, some of the gold in that watch could have been mined by the Romans 2,000 years ago," says James Turk. The way gold is being used in the technology industry, however, is different. The British Geological Survey states that about 12% of current world gold production finds its way to this sector, where it is often used in such small quantities, in each individual product, that it may no longer be economical to recycle it. In short, gold may be being "consumed" for the first time. More on This Story
Starting Your Career as aQuant，you should read these books.以下推荐书目，由华尔街的Quant们和美国各名牌大学毕业生推荐。 FREE QUANT CAREER GUIDES What do quant do ? A guide by Mark Joshi. Download Paul Dominic's Guide to Quant Careers (see attachment) Career in Financial Markets 2011- a guide by efinancialcareers. Download Interview Preparation Guide by Michael Page: Quantitative Analysis. Download Interview Preparation Guide by Michael Page: Quantitative Structuring. Download Paul Dominic's Job Hunting in Interesting Times Second Edition (see attachment) Peter Carr's A Practitioner's Guide to Mathematical Finance (see attachment) GENERAL READING ON WALL STREET Reminiscences of a Stock Operator (Wiley Investment Classics) Working the Street: What You Need to Know About Life on Wall Street Liar’s Poker: Rising Through the Wreckage on Wall Street Monkey Business: Swinging Through the Wall Street Jungle Fiasco: The Inside Story of a Wall Street Trader Den of Thieves When Genius Failed: The Rise and Fall of Long-Term Capital Management Traders, Guns Money: Knowns and unknowns in the dazzling world of derivatives The Greatest Trade Ever: The Behind-the-Scenes Story of How John Paulson Defied Wall Street and Made Financial History Goldman Sachs : The Culture of Success The House of Morgan: An American Banking Dynasty and the Rise of Modern Finance Wall Street: A History: From Its Beginnings to the Fall of Enron The Murder of Lehman Brothers: An Insider’s Look at the Global Meltdown On the Brink: Inside the Race to Stop the Collapse of the Global Financial System House of Cards: A Tale of Hubris and Wretched Excess on Wall Street Too Big to Fail: The Inside Story of How Wall Street and Washington Fought to Save the Financial System-and Themselves Liquidated: An Ethnography of Wall Street Fortune’s Formula: The Untold Story of the Scientific Betting System That Beat the Casinos and Wall Stree t CAREER AS A QUANT My Life as a Quant: Reflections on Physics and Finance How I Became a Quant: Insights from 25 of Wall Street’s Elite The Big Short: Inside the Doomsday Machine The Quants: How a New Breed of Math Whizzes Conquered Wall Street and Nearly Destroyed It Nerds on Wall Street: Math, Machines and Wired Markets Physicists on Wall Street and Other Essays on Science and Society The Complete Guide to Capital Markets for Quantitative Professionals Starting Your Career as a Wall Street Quant: A Practical, No-BS Guide to Getting a Job in Quantitative Finance and Launching a Lucrative Career BOOKS FOR QUANT INTERVIEWS Heard on The Street: Quantitative Questions from Wall Street Job Interviews by Timothy Crack Quant Job Interview Questions And Answers by Mark Joshi Frequently Asked Questions in Quantitative Finance by Paul Wilmott A Practical Guide To Quantitative Finance Interviews by Xinfeng Zhou Basic Black-Scholes: Option Pricing and Trading by Timothy Crack Fifty Challenging Problems in Probability with Solutions by Frederick Mosteller Vault Guide to Advanced Finance Quantitative Interviews GOOD BOOKS TO READ BEFORE STARTING MFE PROGRAM A Primer for the Mathematics of Financial Engineering (+ Solutions Manual ) by Dan Stefanica An Introduction to the Mathematics of Financial Derivatives, Second Edition by Salih Neftci Options, Futures, and Other Derivatives with Derivagem CD (7th Edition) by John Hull Paul Wilmott on Quantitative Finance 3 Volume Set (2nd Edition) by Paul Wilmott Principles of Financial Engineering, Second Edition by Salih Neftci Elementary Stochastic Calculus With Finance in View by Thomas Mikosch The Concepts and Practice of Mathematical Finance by Mark Joshi Financial Options: From Theory to Practice by Stephen Figlewski Financial Calculus : An Introduction to Derivative Pricing by Martin Baxter A Course in Financial Calculus by Etheridge Alison The Mathematics of Financial Derivatives: A Student Introduction by Paul Wilmott Frequently Asked Questions in Quantitative Finance by Paul Wilmott Derivatives Markets by Robert L. McDonald An Undergraduate Introduction to Financial Mathematics by Robert Buchanan PROGRAMMING C++ (ordered by level of difficulty) Problem Solving with C++, 7th Edition by Walter Savitch C++ How to Program (7th Edition) by Harvey Deitel Absolute C++ (4th Edition) by Walter Savitch Thinking in C++: Introduction to Standard C++, Volume One by Bruce Eckel Thinking in C++: Practical Programming, Volume Two by Bruce Eckel The C++ Programming Language: Special Edition by Bjarne Stroustrup (C++ inventor) Effective C++: 55 Specific Ways to Improve Your Programs and Designs by Scot Myers C++ Primer (4th Edition) by Stanley Lippman C++ Design Patterns and Derivatives Pricing (2nd edition) by Mark Joshi Financial Instrument Pricing Using C++ by Daniel Duffy C# (ordered by level of difficulty) C# 2010 for Programmers (4th Edition) Computational Finance Using C and C# by George Levy C# in Depth, Second Edition by Jon Skeet F# (ordered by level of difficulty) Programming F#: An introduction to functional language by Chris Smith F# for Scientists by Jon Harrops (Microsoft Researcher) Real World Functional Programming: With Examples in F# and C# Expert F# 2.0 by Don Syme Beginning F# by Robert Pickering Matlab (ordered by level of difficulty) Matlab: A Practical Introduction to Programming and Problem Solving Numerical Methods in Finance and Economics: A MATLAB-Based Introduction (Statistics in Practice)
March Spending Driven By Surge In Services The latest personal income and expenditure report for March was of particularly interesting reading. However, as opposed to the mainstream headlines that immediately reported that despite higher payroll taxes consumers were still spending, and therefore a sign of a strong economy, it was where they were spending that was most telling. As I searched the various headlines, and read several of the economic releases, I came across only one analysis that questioned the headline report. Tyler Durden at Zero Hedge: "Despite expectations that following several months of subpar income growth offset by rampaging spending and thus a plunging savings rate, March incomes would rise by 0.4%, while spending would be flat, this did not happen, and instead both spending and incomes rose by the same amount, or 0.2% in the past month. Worse, when adjusting for inflation, real disposable income rose just 1.1% compared to last March, and just barely above the 0% breakeven. On the other side, real spending was up 2.2% Y/Y just barely above the 2% recessionary threshold. And even that number is misleading as spending on Total Goods (including durable, already known as being quite abysmal, and non-durable), dropped by $32.8 billion in nominal dollars. What was the offset? Why a massive surge in consumption expenditures on services, which rose by $53.8 billion, which absent the spending aberration for September 11, 2001, which was reversed in the following month, was the biggest monthly increase on record! What drove this record services spending spree is anyone's guess." Tyler is correct and the chart of the monthly dollar change in services spending shows it to be the largest single monthly increase since January 2002. However, we don't have to "guess" at where the dollars were spent - all we have to do is dig down into the report. In the month of March, as noted above, the increase in services related spending offset the decline in both durable and non-durable goods spending. The chart below shows PCE, and its major subcomponents, on a net dollar and net percentage change from February to March. Of course, as Tyler correctly questioned, where were the dollars on "services" actually spent. For clarification the category of "services" comprises any item that is immediately consumed. This category covers everything from housing to financial services to food to transportation. The next chart below shows the major sub-categories of the "services" component of overall PCE. As you can see consumers spent almost 50% of their money on housing and utilities in March. The stuff that we produce, which has the largest multiplier in the economy, declined which speaks to the weakness seen in all of the recent manufacturing reports. However, if we dig down into the services sector, we can quickly find the reason that consumers are spending less on manufactured goods as their utility costs jumped sharply in March as several cold fronts ran accross the nation. The chart below shows the total increase in services consumption in March, the total spent on household utilities and the total of household utilities spent on electricity and gas. However, as we analyze the services sector spending in more detail, there are some other very interesting data points as it relates to the consumer. The chart below shows the various subcomponents of the services category that had the biggest net percentage change in March. What immediately jumps out is the decrease in bank and securities related fees. With the market surging to all-time highs, and the media chastising individuals for not chasing the markets, you would expect to see these figures rising. Alas, that is not the case and more of individuals disposable income is being diverted into not only utilities, but also public transportation, clothing repair, internet access, personal care labor union dues and employment agencies. The ongoing theme seems to be job hunting. With incomes not rising fast enough to offset real inflation, and more individuals having ever tougher times making ends meet, it appears that they are beginning to clean themselves up and go looking for additional work. Of course, when you aren't looking for work, and need to fill some time, it appears that the onset of spring, is drawing individuals into movie theaters and sporting arenas - including casinos. As a side note - it is mildly amusing is the casino gambling is up while commissions for the largest casino on the planet, the stock market, are down. Maybe individuals are catching on that they have a better chance of winning in Vegas. However, the bottom line is that if you want to know where individuals are spending the bulk of their money in the most recent month - 73% of the money spent on "services" fell into four major categories. The personal income and spending report does little to brighten the economic picture. As we have been discussing over the past couple of weeks, see here and here , the economy clearly peaked in 2011 and has been slowing since. Despite the Fed's inflation of asset prices - there is little translation into the real economy. As we discussed i n this past weekend's newsletter the disconnect between the economy, and the markets, continues to widen due to liquidity driven interventions, the suppression of interest rates and the Central Bank's direct purchases of equities. The reality is that we now live in a world where "freely traded markets" are an anachronism and fundamental rules simply no longer apply. However, the problem is that such actions continually lead to asset bubbles, and eventual busts, that not only impact economic stability but destroy the financial stability of families. The risk is not lost on the Federal Reserve as Minneapolis Fed President Kocherlakota recently stated: "Unusually low real interest rates should be expected to be linked with inflated asset prices, high asset return volatility and heightened merger activity. All of these financial market outcomes are often interpreted as signifying financial market instability... may only be able to achieve its macroeconomic objectives in association with signs of instability in financial markets. These financial market phenomena could pose macroeconomic risks." In other words the only way for the Fed to achieve its goals of inflating the economy is to create an asset bubble. Of course, the insanity is that once the goals are achieved the asset bubble busts and then the process must be started all over again. Of course, through the long course of the Federal Reserve's ongoing interventions into the economy they have never witnessed an asset bubble before it burst and they are unlikely to do so this time either. The consumer is clearly delivering a message about the state of the real economy. Eventually, the disconnect between the economy and the markets will merge. Unfortunately, there is no historical evidence of such reversions being a positive event. Average: 4.142855 Your rating: None Average: 4.1 ( 7 votes)
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