R Packages
The forecast package uses the base R graphics for all plots, but some people may prefer to use the nice graphics available using the ggplot2 package. In the following two posts, Frank Davenport shows how it can be done: To leave a comment for the author, please follow the link and comment on his blog: Research tips » R . R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: visualization ( ggplot2 , Boxplots , maps , animation ), programming ( RStudio , Sweave , LaTeX , SQL , Eclipse , git , hadoop , Web Scraping ) statistics ( regression , PCA , time series , ecdf , trading ) and more... <p style="text-align:right;color:#A8A8A8"></p>
Forecasts and ggplot
Linear regression is one of the key concepts in statistics [ wikipedia1 , wikipedia2 ]. However, people are often confuse the meaning of parameters of linear regression - the intercept tells us the average value of y at x=0, while the slope tells us how much change of y can we expect on average when we change x for one unit - exactly the same as in the linear function , though we use averages here due to noise. Today colleague got confused with the meaning of adjusting covariate (x variable) and the effect of parameter estimates. By shifting the x scale, we also shift the point at which intercept is estimated. I made the following graph to demonstrate this point in the case of nested regression of y on x within a group factor having two levels.
Regression – covariate adjustment
sixty twotorials now posted. two minutes each. new video highlights: purpose.of.twotorials.com <- ifelse( you are not yet fluent in the r language , help you learn more , provide quicklinks to answer colleagues' r questions )
sixty two-minute r twotorials now available
Using R for Analyzing Loans, Portfolios and Risk: From Academic Theory to Financial Practice
View the recorded webinar: Dr. Sanjiv Das has held positions as at Citibank, Harvard University Professor and Program Director at the FDIC’s Center for Financial Research.
User Input in R vs Python
Both R and Python have facilities where the coder can write a script which requests a user to input some information. In Python 2.6, the main function for this task is raw_input (in Python 3.0, it’s input()). In R, there are a series of functions that can be used to request an input from the user, including readline(), cat(), and scan(). However, I find the readline() function to be the optimal function for this task.
I treat this matter with other software´s, and of course you can do the same with "R". Once I have the spectra of my samples with a math treatment, I want to draw a correlation spectrum to see which wavelengths have better correlation with the constituent of interest. In this example I want to see the correlation of the wavelengths treated with MSC (Multiple Scatter Correction) respect to the Moisture value of the Demo file, but only in the NIR range (1100 to 2498 nm = 700 data points). >Xmsc<-demoNIR_msc$NIRmsc >Ymoi<-demoNIR_msc$Moisture >cor_spec<-cor(Ymoi,Xmsc[,1:700]) >matplot(wave_nir,t(cor_spec),lty=1,pch="*",
"Correlation / Covariance" Spectrum (This time with "R")
Registration is now open for R/Finance 2012 in Chicago, the conference devoted to applications of R in the financial sector . The program has also been announced, with topics including: modelling insurance claim reserves; risk management in power markets; peer performance of hedge funds; hedging event risk; operational risk measurement with R and RevoScaleR ; and many other applications of R. Here's conference announcement from the organizers: The registration for R/Finance 2012 -- which will take place May 11 and 12 in Chicago -- is NOW OPEN!
finance
This CRAN task view contains a list of packages which offer facilities for solving optimization problems. Although every regression model in statistics solves an optimization problem they are not part of this view. If you are looking for regression methods, the following views will contain useful starting points: Multivariate , SocialSciences , Robust among others. The focus of this task view is on Optimization Infrastructure Packages , General Purpose Continuous Solvers , Mathematical Programming Solvers and Specific Applications in Optimization .
CRAN Task View: Optimization and Mathematical Programming
boxcox {MASS}
Box-Cox Transformations for Linear Models Description Computes and optionally plots profile log-likelihoods for the parameter of the Box-Cox power transformation. UsageDescription forecast is a generic function for forecasting from time series or time series models. The function invokes particular methods which depend on the class of the first argument. For example, the function forecast.Arima makes forecasts based on the results produced by arima . The function forecast.ts makes forecasts using ets models (if the data are non-seasonal or the seasonal period is 12 or less) or stlf (if the seasonal period is 13 or more).
