## Successive Differences of a Randomly-Generated Timeseries

November 25, 2012
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I was wondering about the null distribution of successive differences of random sequences, and decided to do some numerical experiments. I quickly realized that successive differences equates to taking successively higher-order numerical derivatives, ...

## Hello world!

November 25, 2012
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Welcome to WordPress.com! This is your very first post. Click the Edit link to modify or delete it, or start a new post. If you like, use this post to tell readers why you started this blog and what you plan to do with it. Happy blogging!Filed under: U...

## Modis R: Package tutorial

November 24, 2012
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The MODIS package for R For people who work in GIS in R there has been a bit of challenge in working with data from  Modis. I’ll use an example from my own work on UHI to illustrate. A while back I decided that I wanted to look at albedo data from MODIS.  If you

## Run R Code Within Python On The Fly

November 24, 2012
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Below is an example showing how to run R code within python, which is an extremely attractive feature for hardcore R programmers.

## Simulating weak gravitational lensing

November 24, 2012
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In the search for dark matter, I have been having mixed success. It seems that locating DM in single halo skies is a fairly straightforward problem. However, when there are more than one halo, things get quite a bit trickier. As I have advocated many times before, including here and here, simulation can provide deep

## Personal CRAN-repository

November 24, 2012
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Offering - the backbone of open source. The image is CC by TenthMusePhotography This is part II of the previous package creation post. I've created my own CRAN repository since I wanted a quick upload. Perhaps in the future I'll post on the main server but right now...

## Secret Santa – unfinished business

November 24, 2012
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Last week I wrote:This is actually a more difficult calculation (or I forgot too much probability). Luckily a bit of brute force comes in handy. To reiterate, in general simulated data shows 0.54 redraws because of the first person etc.colSums(countsto...

## ESSA2013 Conference

November 24, 2012
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It has been just announced that during ESSA2013 conference I am planning to organize a special track on "Statistical analysis of simulation models". I hope to get some presentations using GNU R to promote it in social simulation community.It is obvious that GNU R excels in analysis of simulation data. However, very often it can be neatly...

## A Light Touch on RPy2

November 23, 2012
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For a statistical analyst, the first step to start a data analysis project is to import the data into the program and then to screen the descriptive statistics of the data. In python, we can easily do so with pandas package. Tonight, I’d like to add some spice to my python learning experience and do

## R is (Almost) Platform Independent

November 23, 2012
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I write R scripts on both my laptop and desktop, so the main issue I have is making sure that the R scripts are updated on these devices. There are several ways to ensure this happens:Use a version control system (on the cloud), e.g GithubWrite R scrip...

## Shootout 2012 : first PLS regressions

November 23, 2012
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It´s time to start developing some regressions in order to find the best math treatment, the best number of terms, the best spectral regions, the best regression method,....This time I´m working with the PLS  package in R, and just to make ...

## Opting for shorter movies, be aware u might be cutting the entertainment too!

November 23, 2012
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Hello Friends,This time I thought to bring in little more spice and thought of focusing on movies.  I don’t know about you but I am a movie buff. Often on a weekend when I am trying to pick up a movie from my movie repository, which spans to some TBs now, I feel little lost.  Apart from a general...

## xts and GSOC 2012

November 23, 2012
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Josh Ulrich and Jeff Ryan mentored a Google Summer of Code (GSOC) project this summer focused on experimental functionality for xts in collaboration with R. Michael Weylandt, a student in operations research and financial engineering from Princeton. You might recognize Michael from his presentation at R/Finance this year, where he gave a talk entitled “A

## ggplot2 Tutorial

November 23, 2012
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Here is a link to a wonderful ggplot2 tutorial: http://www.ceb-institute.org/bbs/wp-content/uploads/2011/09/handout_ggplot2.pdf by R. Saccilotto and the Basel Institute for Clinical Epidemiology …Continue reading »

## IPython vs knitr, or Python vs R

November 23, 2012
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I watched this video by Fernando Pérez a few days ago when I was reading a comment by James Correia Jr on Simply Statistics: This is absolutely a fantastic talk that I recommend everybody to watch (it is good in both the form and content). Not surprisingly, I started thinking ipython vs knitr. Corey Chivers said we could...

## project euler: problem 61

November 22, 2012
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Triangle, square, pentagonal, hexagonal, heptagonal, and octagonal numbers are all figurate (polygonal) numbers and are generated by the following formulae: Triangle P3,n=n(n+1)/2 1, 3, 6, 10, 15, ... Square P4,n=n2 ...

## Escaping the simplex, part 1

November 22, 2012
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Before tackling the main subject, two quick notes:I did not post for quite a while in part because I followed the Coursera online course Introduction to Computational Finance and Financial Econometrics.  It was a nice refresher, extremely well pre...

## Peer-reviewed R packages?

November 22, 2012
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Dear R-Users, a question: I am the author of the ‘qpcR’ package. Within this, there is a function ‘propagate’ that does error propagation based on Monte Carlo Simulation, permutation-based confidence intervals and Taylor expansion. For the latter I recently implemented a second-order Taylor expansion term that can correct for nonlinearity. The formulas are quite complex

## nice ggplot intro tutorial. Just run the commands, about 6 pages…

November 22, 2012
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nice ggplot intro tutorial. Just run the commands, about 6 pages = flexible 1-3 hours of learning, depending how much reading you want to pair it with by Ramon Saccilotto

## We NEED more data

November 22, 2012
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Email One of the historic difficulties of doing research on urban energy systems has been the limited availability of data at sufficiently detailed spatial resolutions. Without this data, you might end up relying on aggregate information about the built environment, building occupants, and local geography that doesn't apply to the specifics of a particular neighbourhood

## Washington Gave Thanks To R:

November 22, 2012
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The folks over at is.R() brought along an "adorable Turkey". I guess we'll thank them for their gift - and pardon the Turkey. Personally I thank them for a bucket of hints and tricks I freely used and will continue to do so.Tal brought us a great ...

## Connecting R to an Oracle database with RJDBC

November 22, 2012
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In many circumstances, you might want to connect R directly to a database to store and retrieve data.  If the source database is an Oracle database, you have a number of options: ROracle RODBC RJDBC   Using ROracle should theoretically… Read more ›

## Controlling heatmap colors with ggplot2

November 22, 2012
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One of the most popular posts on this blog is the very first one, solving the issue of mapping certain ranges of values to particular colors in heatmaps. Given the abundance of ggplot2 usage in R plotting, I thought I’d … Continue reading →

## Happy Thanksgiving from is.R()!

November 22, 2012
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Today’s post is mostly to wish everyone a Happy Thanksgiving. We will be taking the rest of the week off, and will return on Monday. Below is some code to reproduce the adorable Turkey above; enjoy! https://gist.github.com/4122464

## Extending Commodity time series

November 21, 2012
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I want to follow up with Extending Gold time series post by showing how we can extend Commodity time series. Most Commodity ETFs began trading in 2006, please see the List of Commodity ETFs page. I will use DBC – PowerShares DB Commodity Fund, one on the most liquid Commodity ETFs as my proxy for

## What’s the difference between POSIXct and POSIXlt?

November 21, 2012
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POSIXct is the signed number of seconds since “the epoch”. For example it was 1351298112 UTC (GMT) when I wrote this. (1351298112 UTC = Sat Oct 27, 2:35 am GMT = Fri Oct 26, 8:35 pm EST = Fri Oct 26, 5:35 pm PST = 2:35 pm HST) POSIXlt is one of many text | character | string formats such as: May 17, 2017 17/5/2017 17-5-17 05:24:39

## Data types, part 3: Factors!

November 21, 2012
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In this third part of the data types series, I'll go an important class that I skipped over so far: factors.Factors are categorical variables that are super useful in summary statistics, plots, and regressions. They basically act like dummy variables t...

## Upcoming Webinar: Real-time, big-data analytics

November 21, 2012
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A quick heads-up that I'll be presenting another brand-new webinar on Thursday next week (November 29). In Real-time Big Data Analytics: From Deployment to Production, I'll review the process of making predictive models work in real-live operational environments. I'll also tackle those ubiquitous buzz-words "real-time" and "big data", and the fact that they can mean very different things in...

## IPython vs RStudio+knitr

November 21, 2012
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At a meeting last night with some collaborators at the Vélobstacles project, I was excitedly told about the magic of IPython and it’s notebook functionality for reproducible research. This sounds familiar, I thought to myself. Using a literate programming approach to integrate computation with the communication of methodology and results has been at the core