quanteda (version 0.9.6-1)

cbind.dfm: Combine dfm objects by Rows or Columns

Description

Take a sequence of dfm-class objects and combine by columns or rows, returning a dfm with the combined documents or features, respectively.

Usage

## S3 method for class 'dfm':
cbind(...)
## S3 method for class 'dfm':
rbind(...)

Arguments

...

dfm objects to be joined column-wise (cbind) or row-wise (rbind) to the first

Details

cbind(x, y, ...) combines dfm objects by columns, returning a dfm object with combined features from input dfm objects. Note that this should be used with extreme caution, as joining dfms with different documents will result in a new row with the docname(s) of the first dfm, merging in those from the second. Furthermore, if features are shared between the dfms being cbinded, then duplicate feature labels will result. In both instances, warning messages will result.

rbind(x, y, ...) combines dfm objects by rows, returning a dfm object with combined features from input dfm objects. Features are matched between the two dfm objects, so that the order and names of the features does not need to match. The resulting row combined dfm will have its features alphabetically sorted. The matching is performed by rbind2 defined for object classes in the Matrix package. The attributes and settings of this new dfm are not currently preserved.

Examples

# cbind() for dfm objects
(dfm1 <- dfm("This is one sample text sample.", verbose = FALSE))
(dfm2 <- dfm("More words here.", verbose = FALSE))
cbind(dfm1, dfm2)

# rbind() for dfm objects
(dfm1 <- dfm(c(doc1 = "This is one sample text sample."), verbose = FALSE))
(dfm2 <- dfm(c(doc2 = "One two three text text."), verbose = FALSE))
(dfm3 <- dfm(c(doc3 = "This is the fourth sample text."), verbose = FALSE))
rbind(dfm1, dfm2)
rbind(dfm1, dfm2, dfm3)