polmineR (version 0.8.3)

textstat-class: S4 textstat superclass.

Description

The textstat-class (technically an S4 class) serves as a superclass for the classes features, context, and partition. Usually, the class will not be used directly. It offers a set of standard generic methods (such as head, tail, dim, nrow, colnames) its childs inherit. The core feature of textstat and its childs is a data.table in the slot stat for keeping data on text statistics of a corpus, or a partition.

Usage

# S4 method for textstat
name(x)
# S4 method for character
name(x)
# S4 method for textstat
name(x) <- value
# S4 method for textstat
round(x, digits = 2L)
# S4 method for textstat
sort(x, by, decreasing = TRUE)
as.bundle(object, ...)
# S4 method for textstat,textstat
+(e1, e2)
# S4 method for textstat
subset(x, subset)
# S3 method for textstat
as.data.table(x, ...)
# S4 method for textstat
show(object)
# S4 method for textstat
p_attributes(.Object)
# S4 method for textstat
knit_print(x, options = knitr::opts_chunk, ...)
# S4 method for textstat
get_corpus(x)
# S4 method for textstat
format(x, digits = 2L)
# S4 method for textstat
view(.Object)

Arguments

x

A textstat object.

value

A character vector to assign as name to slot name of a textstat class object.

digits

Number of digits.

by

Column that will serve as the key for sorting.

decreasing

Logical, whether to return decreasing order.

object

a textstat object

...

Further arguments.

e1

A texstat object.

e2

Another texstat object.

subset

A logical expression indicating elements or rows to keep.

.Object

A textstat object.

options

Chunk options.

Slots

p_attribute

Object of class character, p-attribute of the query.

corpus

A corpus specified by a length-one character vector.

stat

A data.table with statistical information.

name

The name of the object.

annotation_cols

A character vector, column names of data.table in slot stat that are annotations.

encoding

A length-one character vector, the encoding of the corpus.

Details

A head-method will return the first rows of the data.table in the stat-slot. Use argument n to specify the number of rows.

A tail-method will return the last rows of the data.table in the stat-slot. Use argument n to specify the number of rows.

The methods dim, nrow and ncol will return information on the dimensions, the number of rows, or the number of columns of the data.table in the stat-slot, respectively.

Objects derived from the textstat class can be indexed with simple square brackets ("[") to get rows specified by an numeric/integer vector, and with double square brackets ("[[") to get specific columns from the data.table in the slot stat.

The colnames-method will return the column names of the data-table in the slot stat.

The methods as.data.table, and as.data.frame will extract the data.table in the slot stat as a data.table, or data.frame, respectively.

textstat objects can have a name, which can be retrieved, and set using the name-method and name<-, respectively.

The round()-method looks up all numeric columns in the data.table in the stat-slot of the textstat object and rounds values of these columns to the number of decimal places specified by argument digits.

The format()-method returns a pretty-printed and minimized version of the data.table in the stat-slot of the textstat-object: It will round all numeric columns to the number of decimal numbers specified by digits, and drop all columns with token ids. The return value is a data.table.

Examples

# NOT RUN {
use("polmineR")
P <- partition("GERMAPARLMINI", date = ".*", p_attribute = "word", regex = TRUE)
y <- cooccurrences(P, query = "Arbeit")

# generics defined in the polmineR package
x <- count("REUTERS", p_attribute = "word")
name(x) <- "count_reuters"
name(x)
get_corpus(x)

# Standard generic methods known from data.frames work for objects inheriting
# from the textstat class

head(y)
tail(y)
nrow(y)
ncol(y)
dim(y)
colnames(y)

# Use brackets for indexing 

# }
# NOT RUN {
y[1:25]
y[,c("word", "ll")]
y[1:25, "word"]
y[1:25][["word"]]
y[which(y[["word"]] %in% c("Arbeit", "Sozial"))]
y[ y[["word"]] %in% c("Arbeit", "Sozial") ]
# }
# NOT RUN {
sc <- partition("GERMAPARLMINI", speaker = "Angela Dorothea Merkel")
cnt <- count(sc, p_attribute = c("word", "pos"))
cnt_min <- subset(cnt, pos %in% c("NN", "ADJA"))
cnt_min <- subset(cnt, pos == "NE")

# Get statistics in textstat object as data.table
count_dt <- corpus("REUTERS") %>%
  subset(grep("saudi-arabia", places)) %>% 
  count(p_attribute = "word") %>%
  as.data.table()
# }