R Basics - bcb420-2023/Jielin_Yang GitHub Wiki

summary(object) # returns a named vector

summary(object)[index]

# define matrix
a <- c(1, 2, 3, 4, 5, 6)
dim(a) <- c(2, 3)
dim(a)
rbind()
cbind()

# Read to dataframe
read.table(file = ,
           sep = "\t",
           header = TRUE,
           stringsAsFactors = FALSE)

# Iterate over a list and apply the function on all elements
lappy(someList, someFunction(x) {defineFunction})

# sort an object
order(someCollection)

# text matching
grep()  # return vector of indices
grepl() # return vector of TRUE FASLE

# Built-in conditionals
all()
any()
exists()  # whether an object exists
is.()

# Logical operations
x | y     # vectorized
x & y   
x || y    # non-vectorized, coerce to the first Boolean operation
x && y  

# Generics
methods(seq)  # what specific methods does seq provide
getAnywhere(seq.default())   # Get the code of the default seq method

# Generic plots in R
plot()
pie()
hist()
stripchart()
stem()
barplot()
boxplot()

# Plotting
# Color palette in R defined by names can be found at
https://bcb420-2023.github.io/R_basics/r-plots.html#colours-by-name

# Lines
# argument lty for line type
#          lwd for line width

# Plotting layout
par()   # current plotting parameters
opar <- par(arguments)  # set the plotting parameters
par(opar)   # reset to default

# Task 23
begin <- 3
txt <- as.character()
while (begin >= 0) {
  txt <- c(txt, as.character(begin))
  begin <- begin - 1
}
txt <- c(txt, "Lift Off!")
txt