How to control the limits of data values in R plots.
R has multiple graphics engines. Here we will talk about the base graphics and the ggplot2 package.
We’ll create a bit of data to use in the examples:
one2ten <- 1:10
ggplot2 demands that you have a data frame:
ggdat <- data.frame(first=one2ten, second=one2ten)
Seriously exciting data, yes?
The default is — not surprisingly — to create limits so that the data comfortably fit. Read more →
Several packages on CRAN provide (or relate to) interfaces between databases and R. Here is a summary, mostly in the words of the package descriptions. Remember that package names are case-sensitive.
The packages that talk about being DBI-compliant are referring to the DBI package (see below in “Other SQL”).
dbConnect: Provides a graphical user interface to connect with databases that use MySQL.
RMySQL: The current version complies with the database interface definition as implemented in the package DBI 0.2-2.
TSMySQL: TSMySQL provides a MySQL interface for TSdbi. Comprehensive examples of all the TS* packages are provided in the vignette Guide.pdf with the TSdata package. Read more →
There is a mechanism that allows variability in the arguments given to R functions. Technically it is ellipsis, but more commonly called “…”, dots, dot-dot-dot or three-dots.
The three-dots allows:
The two prime cases are the c and list functions:
> c
function (..., recursive = FALSE) .Primitive("c")
> list
function (...) .Primitive("list")
Both of these allow you to give them as many arguments as you like, and you can name those arguments (which end up as names in the resulting object). Read more →
Many people are of the opinion that R has a corner on convenient data analysis. That may or may not be true.
But now R literally has a corner that makes data analysis more convenient. If you have a data frame or a matrix with a few columns, then you can use head and/or tail to make sure that it looks as you expect. However, the result is unappetizing if there are hundreds or thousands of columns.
That is is where corner comes in. It shows you the first or last few rows of the first or last few columns.
The mtcars dataset can serve as an example even though it isn’t exactly a gigantic dataset.
By default the first 6 rows and first 6 columns are extracted:
> corner(mtcars) mpg cyl disp hp drat wt Mazda RX4 21.0 6 160 110 3.90 2.620 Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 Datsun 710 22.8 4 108 93 3.85 2.320 Hornet 4 Drive 21.4 6 258 110 3.08 3.215 Hornet Sportabout 18.7 8 360 175 3.15 3.440 Valiant 18.1 6 225 105 2.76 3.460
The same thing is done with: Read more →
