[R] Learning ANOVA

[Erik Iverson]

> Performed following steps on R:-
> 
> ### to access to the object
>> data(InsectSprays)
> 
> ### create a .csv file
>> write.csv(InsectSprays, "InsectSpraysCopy.csv")
> 
> 
> On another terminal
> $ sudo updatedb
> $ locate InsectSpraysCopy.csv
> /home/userA/InsectSpraysCopy.csv
> 
> 
> ### Read in some data
>> test01 <- read.csv(file.choose(), header=TRUE)
> 
> Enter file name: /home/userA/InsectSpraysCopy.csv

I either don't understand what you're doing, or you seem
very confused.

R comes with many sample data sets for you to use.

You can see a list of them using the ?data function.

Calling data with an argument loads that dataset.

So, when you type:

 > data(InsectSprays)

that data object is now available in R, see

 > objects()

You can look at it simply by printing it:

 > InsectSprays

If for some reason it makes sense to do it this way for your
use case, then that's fine, I just want to make sure you understand
that you don't have to if accessing built-in datasets is all you want.

> ### Look at the data
>> test01
>     X count spray
> 1   1    10     A
> 2   2     7     A
> 3   3    20     A

<snip>

> ### Create a side-by-side boxplot of the data
> boxplot(test01$DO ~ test01$Stream)
> Error in model.frame.default(formula = test01$DO ~ test01$Stream) : 
>   invalid type (NULL) for variable 'test01$DO'

Why do you think test01 has an element called "D0" or "Stream"?? The
column names when you print the data tell you otherwise!