BAT 402 - R Commands Simple Reviewer

A review set of vocabulary flashcards covering basic R commands, functions, and operations from BAT 402.

str(df)

Shows the structure of the dataset, including column types and sample values.

head(df)

Shows the first 6 rows.

dim(df)

Shows the number of rows and columns.

summary(df)

Gives a quick statistical summary of the dataset.

mean(df$column_name)

Finds the average.

median(df$column_name)

Finds the middle value.

sum(df$column_name)

Adds all values together.

max(df$column_name)

Finds the largest value.

min(df$column_name)

Finds the smallest value.

table(df$column_name)

Counts how often each value/category appears.

is.na(df$column_name)

Checks which values are missing (NA).

colSums(is.na(df))

Counts missing values in each column.

colMeans(is.na(df))

Finds the proportion of missing values in each column.

round(…, 1)

Rounds a result to 1 decimal place.

df$column_name[is.na(df$column_name)] <- "value"

Fills missing values with a chosen value/category.

median(df$column_name, na.rm=TRUE)

Finds the median while ignoring missing values.

mean(df$column_name, na.rm=TRUE)

Finds the mean while ignoring missing values.

duplicated(df)

Checks which rows are duplicates.

sum(duplicated(df))

Counts the duplicate rows.

df[duplicated(df), ]

Displays the duplicate rows.

summary(df$column_name)

Check the minimum and maximum for unusual values.

boxplot(df$column_name, main = "…", ylab = "…")

Creates a boxplot to visualize the distribution and possible outliers.

main = "…"

Sets the graph title.

ylab = "…"

Sets the Y-axis label.

df$column_name[df$column_name == 12000] <- 12

Replaces an incorrect value.

df

Keeps only rows where the column is greater than 0.

Assignment operator. Stores a value/result.

==

Checks if two values are equal.

>

Checks if one value is greater than another.

as.Date(df$column_name)

Converts a column to Date type.

as.factor(df$column_name)

Converts a categorical column to factor.

as.character(df$column_name)

Converts a value/column to text.

as.integer(df$column_name)

Converts a value/column to integer.

as.integer(TRUE/FALSE)

Converts TRUE/FALSE to 1/0.

df$column_name <- df$column_name / df$column_name

Creates a new ratio from two columns.

df$column_name <- as.integer(condition)

Creates a 1/0 yes/no flag.

c("value1", "value2")

Combines values into a vector/list.

head(df[, c("column_name", "column_name")])

Shows the first rows of selected columns.

format(df$column_name, "%m")

Extracts the month number from a Date.

as.integer(format(df$column_name, "%m"))

Gets the month as an integer.

weekdays(df$column_name)

Gets the day of the week.

df$column_name %in% c("Saturday", "Sunday")

Checks whether a value is Saturday or Sunday.