Supplement for Lesson-2
by A. Mani & Anne Laure Buisson
Useful Commands:
A is a data frame in the following.
A$colname - extracts column with name ''colname'' use:
A[,i] - extracts the ith column
A[i,] - extracts the ith row
A[[i,j]] - for ij th element
What is A[i,j]?
A[1:3,2] - extract rows 1:3 of column 2
Other Useful Commands:
edit(A) - for editing A
head(A) - extracts the first six rows of A.
tail (A) - extracts the last six rows of A.
names(A) - lists all column names