17 Filters and packages
Filtering data is one of the very basic operation when you work with data. You want to remove a part of the data that is invalid or simply you’re not interested in. Or, you want to zero in on a particular part of the data you want to know more about
For example, in the randu
dataset, how many y
variables are greater than 0.5? 0.6?
length(randu$y[randu$y>0.5])
#> [1] 191
new.randu <- randu$y[randu$y>0.6]
head(new.randu)
#> [1] 0.873416 0.648545 0.826873 0.926590 0.741526 0.846041
length(new.randu)
#> [1] 161
In the randu
dataset, how many z
variables are greater than 0.9? Less than 0.1? Greater than 0.9 or less than 0.1?
17.1 R packages
From Wikipedia, the free encyclopedia, and fount of all knowledge
R packages are extensions to the R statistical programming language. R packages contain code, data, and documentation in a standardised collection format that can be installed by users of R, typically via a centralised software repository such as CRAN (the Comprehensive R Archive Network).
The large number of packages available for R, and the ease of installing and using them, has been cited as a major factor in driving the widespread adoption of the language in data science.