Basic Concepts of R

In the next two videos we will look at some basic concepts in R and a few R variable types specifically Vector, List, and Table

Slides used in the video below may be downloaded here: https://docs.google.com/file/d/0B6w9i0xWpsHWTDhKM1BWbENGY3c

Slides used in the video below may be downloaded here: 

https://docs.google.com/file/d/0B6w9i0xWpsHWeVcxSVdaX1VPc1U

The R script used may be downloaded here (** Please change the extension to .R):

https://docs.google.com/file/d/0B6w9i0xWpsHWUU43Z1A3d2NuY1U

Knitr

RStudio, R and knitr provide a feature set that is perfect fit for reproducible research.  Lets take a look at these features.

Click on the image to download slides

Common Data Files and Formats

Data comes in many formats, the tools that you  use will most likely be able to read and parse data in different formats. I'll talk briefly about data in text format.

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Installing R

Next we will install the tools that we will need for analysis:

For Microsoft Windows:

For Mac OSX

Smoothed Moving Average

We will now look at a few simple averaging methods:

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Lattice Charts

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Lattice Charts Examples

Let’s use sample data available we will use “mtcars” data

library("lattice")
str(mtcars)

## 'data.frame':    32 obs. of  11 variables:
##  $ mpg : num  21 21 22.8 21.4 18.7 18.1 14.3 24.4 22.8 19.2 ...
##  $ cyl : num  6 6 4 6 8 6 8 4 4 6 ...
##  $ disp: num  160 160 108 258 360 ...
##  $ hp  : num  110 110 93 110 175 105 245 62 95 123 ...
##  $ drat: num  3.9 3.9 3.85 3.08 3.15 2.76 3.21 3.69 3.92 3.92 ...
##  $ wt  : num  2.62 2.88 2.32 3.21 3.44 ...
##  $ qsec: num  16.5 17 18.6 19.4 17 ...
##  $ vs  : num  0 0 1 1 0 1 0 1 1 1 ...
##  $ am  : num  1 1 1 0 0 0 0 0 0 0 ...
##  $ gear: num  4 4 4 3 3 3 3 4 4 4 ...
##  $ carb: num  4 4 1 1 2 1 4 2 2 4 ...

head(mtcars)

##                    mpg cyl disp  hp drat    wt  qsec vs am gear carb
## Mazda RX4         21.0   6  160 110 3.90 2.620 16.46  0  1    4    4
## Mazda RX4 Wag     21.0   6  160 110 3.90 2.875 17.02  0  1    4    4
## Datsun 710        22.8   4  108  93 3.85 2.320 18.61  1  1    4    1
## Hornet 4 Drive    21.4   6  258 110 3.08 3.215 19.44  1  0    3    1
## Hornet Sportabout 18.7   8  360 175 3.15 3.440 17.02  0  0    3    2
## Valiant           18.1   6  225 105 2.76 3.460 20.22  1  0    3    1

xyplot(mpg ~ hp | factor(cyl),  ylab="Miles per Gallon (mpg)", xlab="Horse Power (hp)", 
   main="mpg vs hp", data=mtcars, layout = c(3, 1))

histogram (~ mpg | factor(cyl),  xlab="Miles per Gallon (mpg)", main="mpg vs hp", data=mtcars, layout = c(3, 1))

histogram(~ mpg | factor(cyl),  xlab="Miles per Gallon (mpg)", 
   main="mpg vs hp", data=mtcars, layout = c(3, 1), type = "density", panel =      function(x, ...) {
              panel.histogram(x, ...)
              panel.mathdensity(dmath = dnorm, col = "black",
                                args = list(mean=mean(x),sd=sd(x)))
          }
   )