dfm_replace: Replace features in dfm

In quanteda: Quantitative Analysis of Textual Data

Replace features in dfm

Description

Substitute features based on vectorized one-to-one matching for lemmatization or user-defined stemming.

Usage

dfm_replace(
  x,
  pattern,
  replacement,
  case_insensitive = TRUE,
  verbose = quanteda_options("verbose")
)

Arguments

x	dfm whose features will be replaced
pattern	a character vector. See pattern for more details.
replacement	if pattern is a character vector, then replacement must be character vector of equal length, for a 1:1 match.
case_insensitive	logical; if TRUE, ignore case when matching a pattern or dictionary values
verbose	if TRUE print the number of tokens and documents before and after the function is applied. The number of tokens does not include paddings.

Examples

dfmat1 <- dfm(tokens(data_corpus_inaugural))

# lemmatization
taxwords <- c("tax", "taxing", "taxed", "taxed", "taxation")
lemma <- rep("TAX", length(taxwords))
featnames(dfm_select(dfmat1, pattern = taxwords))
dfmat2 <- dfm_replace(dfmat1, pattern = taxwords, replacement = lemma)
featnames(dfm_select(dfmat2, pattern = taxwords))

# stemming
feat <- featnames(dfmat1)
featstem <- char_wordstem(feat, "porter")
dfmat3 <- dfm_replace(dfmat1, pattern = feat, replacement = featstem, case_insensitive = FALSE)
identical(dfmat3, dfm_wordstem(dfmat1, "porter"))

quanteda documentation built on April 4, 2025, 5:20 a.m.