In R: How do I choose the first 4 Rows of a Data Frame

Question

How Do I go about getting the first 4 rows of my Dataframe:

              Weight Response
1   Control     59      0.0
2 Treatment     90      0.8
3 Treatment     47      0.1
4 Treamment    106      0.1
5   Control     85      0.7
6 Treatment     73      0.6
7   Control     61      0.2

In 'R'?

Answer 1

Using the index:

df[1:4,]

Where the values in the parentheses can be interpreted as either logical, numeric, or character (matching the respective names):

df[row.index, column.index]

Read help(`[`) for more detail on this subject, and also read about index matrices in the Introduction to R.

Answer 2

Use head:

dnow <- data.frame(x=rnorm(100), y=runif(100))
head(dnow,4) ## default is 6