Function_name | Package_name | Use |
---|---|---|
as.factor | base | Converts a variable to factors. `as.factor` is a wrapper for the `factor` function. |
cbind | base | Merges matrices. |
CreateTableOne | tableone | Creates a frequency table. |
data.frame | base | Creates a dataset with both numeric and character variables. Requires unique column names and equal length for all variables. |
dim | base | Returns the dimensions of a data frame (rows x columns). |
filter | dplyr | Subsets a dataset by selecting a sub-population. |
function | base | Used to define custom functions, e.g., for calculating standard deviation. |
head | base | Displays the first six elements of an object (e.g., a dataset). `tail` displays the last six. |
is.na | base | Checks for missing values in a variable. |
levels | base | Displays the levels of a factor variable. |
list | base | Stores vectors, matrices, or lists of differing types. |
mode | base | Determines the type of a variable. |
na.omit | base/stats | Removes all rows with missing values from a dataset. |
names | base | Displays names of objects, e.g., variable names of a data frame. |
nlevels | base | Shows the number of levels in a factor variable. |
nrow | base | Returns the dimensions of a data frame. `nrow` gives row count and `ncol` gives column count. |
plot | base/graphics | Draws scatter plots or line graphs. |
base | Prints the output to console. | |
prop.table | base | Displays percentage summary for a table. |
rbind | base | Appends matrices row-wise. |
read.csv | base/utils | Reads data from a CSV file. |
relevel | base/stats | Changes the reference group of a factor variable. |
sasxport.get | Hmisc | Loads data in the SAS format. |
save | base | Saves R objects, such as datasets. |
select | dplyr | Selects specified variables from a dataset. |
set.seed | base | Sets a seed for random number generation ensuring reproducibility. |
str | base/utils | Displays the structure of a dataset, including data type of variables. |
subset | base, dplyr | Subsets a dataset by selecting a sub-population. |
summary | base | Provides a summary of an object, like variable statistics. |
table | base | Displays frequency counts for a variable. |
write.csv | base/utils | Saves a data frame to a CSV file in a specified directory. |
R Functions (W)
This review/summary page provides an extensive list of R functions tailored for data wrangling tasks that we have used in this chapter. Each function is systematically described, highlighting its primary package source and its specific utility.
To learn more about these functions, readers can:
Use R’s Built-in Help System: For each function, access its documentation by prefixing the function name with a question mark in the R console, e.g.,
?as.factor
. This displays the function’s manual page with descriptions, usage, and examples.Search Websites: Simply Google, or visit the CRAN website to search for specific function documentation. Websites like Stack Overflow and RStudio Community often have discussions related to R functions.
Tutorials and Online Courses: Platforms like DataCamp, Coursera, and edX offer R courses that cover many functions in depth. Also there are examples of dedicated R tutorial websites that you might find useful. One example is “Introduction to R for health data analysis” by Ehsan Karim, An Hoang and Qu.
Books: There are numerous R programming books, such as “R for Data Science” by Hadley Wickham and “The Art of R Programming” by Norman Matloff.
Workshops and Webinars: Institutions and organizations occasionally offer R programming workshops or webinars.
Whenever in doubt, exploring existing resources can be highly beneficial.