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# Introduction

The recipes in this chapter are neither obscure numerical calculations nor deep statistical techniques. Yet they are useful functions and idioms that you will likely need at one time or another.

# 12.1. Peeking at Your Data

## Problem

You have a lot of data—too much to display at once. Nonetheless, you want to see some of the data.

## Solution

Use `head` to view the first few data or rows:

`> `head(x)``

Use `tail` to view the last few data or rows:

`> `tail(x)``

## Discussion

Printing a large dataset is pointless because everything just rolls off your screen. Use `head` to see a little bit of the data:

```> `head(dfrm)`
x           y          z
1  0.7533110  0.57562846 -0.1710760
2  2.0143547  0.83312274  0.3698584
3 -0.3551345  0.57471542  2.0132348
4  2.0281678  0.78945319 -0.5378854
5 -2.2168745  0.01758024  1.8344879
6  0.7583962 -1.78214755  2.2848990```

Use `tail` to see the last few rows and the number of rows. Here, we see that this data frame has 10,120 rows:

```> tail(dfrm)
x           y          z
10115 -0.0314354 -0.74988291 -0.2048963
10116 -0.4779001  0.93407510  1.0509977
10117 -1.1314402  1.89308417  1.7207972
10118  0.4891881 -1.20792811 -1.4630227
10119  1.2349013 -0.09615198 -0.9887513
10120 -1.3763834 -2.25309628  0.9296106```

See Recipe 12.15 for seeing the structure of your variable’s contents.

## Problem

You are printing wide datasets. R is wrapping the output, making it hard to read.

## Solution

Set the `width` option to reflect the true number of columns in your output window:

`> `options(width=numcols)``

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