Filtering data in R

Base R

• subset() function:

subset(df, column_name > value)

• subset operator:

filtered_df <- df[df$column_name > 5, ]

• indices in subset operator:

filtered_df <- df[indices, ]

• which() function to extract indices:

# create a data frame
df <- data.frame(name = c("Alice", "Bob", "Charlie", "David"),
                 age = c(25, 35, 40, 30))

# use which() to extract indices of rows where age > 30
indices <- which(df$age > 30)

# use the indices to extract the subset of rows
subset_df <- df[indices, ]

# print the resulting data frame
subset_df

Tidyverse/dplyr

• filter() function: filter() function filters rows based on certain conditions.

subset_df <- filter(df, column_name > 30)
subset_df <- filter(df, column1_name > 30 
                  & column2_name == TRUE)

• slice() function: slice() function selects specific rows.

subset_df <- slice(df, indices)
subset_df <- slice(df, c(1,3))

• select() function: select() function selects specific columns.

subset_df <- select(df, column_name)