textstat_dist_old: Similarity and distance computation between documents or features

Description

These functions compute matrixes of distances and similarities between documents or features from a dfm and return a dist object (or a matrix if specific targets are selected). They are fast and robust because they operate directly on the sparse dfm objects.

Usage

textstat_dist_old(x, selection = NULL, margin = c("documents",
  "features"), method = "euclidean", upper = FALSE, diag = FALSE,
  p = 2)
textstat_simil_old(x, selection = NULL, margin = c("documents",
  "features"), method = "correlation", upper = FALSE, diag = FALSE)

Arguments

a dfm object

selection

a valid index for document or feature names from x, to be selected for comparison

margin

identifies the margin of the dfm on which similarity or difference will be computed: "documents" for documents or "features" for word/term features

method

method the similarity or distance measure to be used; see Details

upper

whether the upper triangle of the symmetric $V \times V$ matrix is recorded

diag

whether the diagonal of the distance matrix should be recorded

The power of the Minkowski distance.

Value

textstat_simil and textstat_dist return dist class objects if selection is NULL, otherwise, a matrix is returned matching distances to the documents or features identified in the selection.

Details

textstat_dist options are: "euclidean" (default), "chisquared", "chisquared2", "kullback". "manhattan", "maximum", "canberra", and "minkowski".

textstat_simil options are: "correlation" (default), "cosine", "jaccard", "ejaccard", "dice", "edice", "simple matching", "hamman", and "faith".

References

The "chisquared" metric is from Legendre, P., & Gallagher, E. D. (2001). "Ecologically meaningful transformations for ordination of species data". Oecologia, 129(2), 271<U+2013>280. doi.org/10.1007/s004420100716

The "chisquared2" metric is the "Quadratic-Chi" measure from Pele, O., & Werman, M. (2010). "The Quadratic-Chi Histogram Distance Family". In Computer Vision <U+2013> ECCV 2010 (Vol. 6312, pp. 749<U+2013>762). Berlin, Heidelberg: Springer, Berlin, Heidelberg. doi.org/10.1007/978-3-642-15552-9_54.

"kullback" is the Kullback-Leibler distance, which assumes that $P(x_i) = 0$ implies $P(y_i)=0$, and in case both $P(x_i)$ and $P(y_i)$ equals to zero, then $P(x_i) * log(p(x_i)/p(y_i))$ is assumed to be zero as the limit value. The formula is: $$\sum{P(x)*log(P(x)/p(y))}$$

All other measures are described in the proxy package.