sample-methods memisc 0.99.25.7

Take a Sample from a Data Frame-like Object

Description

The methods below are convenience short-cuts to take samples from data frames and data sets. They result in a data frame or data set, respectively, the rows of which are a sample of the complete data frame/data set.

Usage

## S4 method for signature 'data.frame'
sample(x, size, replace = FALSE, prob = NULL)
## S4 method for signature 'data.set'
sample(x, size, replace = FALSE, prob = NULL)
## S4 method for signature 'importer'
sample(x, size, replace = FALSE, prob = NULL)

Arguments

x

a data frame or data set.

size

an (optional) numerical value, the sample size, defaults to the total number of rows of x.

replace

a logical value, determines whether sampling takes place with or without replacement.

prob

a vector of sampling probabities or NULL.

Value

A data frame or data set.

Examples

for(.i in 1:4)
 print(sample(iris,5))
   Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
20          5.1         3.8          1.5         0.3     setosa
43          4.4         3.2          1.3         0.2     setosa
23          4.6         3.6          1.0         0.2     setosa
71          5.9         3.2          4.8         1.8 versicolor
51          7.0         3.2          4.7         1.4 versicolor
   Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
45          5.1         3.8          1.9         0.4     setosa
99          5.1         2.5          3.0         1.1 versicolor
98          6.2         2.9          4.3         1.3 versicolor
67          5.6         3.0          4.5         1.5 versicolor
48          4.6         3.2          1.4         0.2     setosa
    Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
105          6.5         3.0          5.8         2.2  virginica
54           5.5         2.3          4.0         1.3 versicolor
78           6.7         3.0          5.0         1.7 versicolor
56           5.7         2.8          4.5         1.3 versicolor
79           6.0         2.9          4.5         1.5 versicolor
   Sepal.Length Sepal.Width Petal.Length Petal.Width    Species
10          4.9         3.1          1.5         0.1     setosa
83          5.8         2.7          3.9         1.2 versicolor
87          6.7         3.1          4.7         1.5 versicolor
66          6.7         3.1          4.4         1.4 versicolor
96          5.7         3.0          4.2         1.2 versicolor