Appendix D Most essential R commands
 Page ID
 3623
This is the short collection of the most frequently used R commands based on the analysis of almost 500 scripts (Figure 3.4.2). For the longer list, check R reference card attached to this book, or R help and manuals.
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Help
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Assign right to left
 [

Select part of object
 $

Call list element by name
 abline()

Add the line from linear regression model
 aov()

Analysis of variation
 as.character()

Convert to text
 as.numeric()

Convert to number
 as.matrix()

Convert to matrix
 boxplot()

Boxplot
 c()

Join into vector
 cbind()

Join columns into matrix
 chisq.test()

Chisquared test
 cor()

Correlation of multiple variables
 colSums()

Sum every column
 cor.test()

Correlation test
 data.frame()

Make data frame
 dev.off()

Close current graphic device
 dotchart()

Replacement for “pie” chart
 example()

Call example of command
 factor()

Convert to factor, modify factor
 file.show()

Show file from disk
 function() ...

Make new function
 head()

Show first rows of data frame
 help()

Help
 hist()

Histogram
 ifelse()

Vectorized condition
 legend()

Add legend to the plot
 library()

Load the installed package
 length()

Length (number of items) of variable
 list()

Make list object
 lines()

Add lines to the plot
 lm()

Linear model
 log()

Natural logarithm
 log10()

Decimal logarithm
 max()

Maximal value
 mean()

Mean
 median()

Median
 min()

Minimal value
 NA

Missed value
 na.omit

Skip missing values
 names()

Show names of elements
 nrow()

How many rows?
 order()

Create order of objects
 paste()

Concatenate two strings
 par()

Set graphic parameters
 pdf()

Open PDF device
 plot()

Graph
 points()

Add points (dots) to the plot
 predict()

Predict values
 q("no")

Quit R and do not save workspace
 qqnorm(); qqline()

Visual check for the normality
 rbind()

Join into matrix by rows
 read.table()

Read data file from disk into R
 rep()

Repeat
 sample()

Random selection
 savehistory()

Save history of commands (does not work under macOS GUI)
 scale()

Make all variables comparable
 sd()

Standard deviation
 source()

Run script
 str()

Structure of object
 summary()

Explain the object, e.g., return main description statistics
 t()

Transpose matrix (rotate on right angle)
 t.test()

Student test (ttest)
 table()

Make contingency table
 text()

Add text to the plot
 url.show()

Show the Internet file
 wilcox.test()

Wilcoxon test
 write.table()

Write to disk