fcm function of quanteda: any possibility of selecting one side of the window

Question

quanteda::fcm(wiki_toks, context = "window", count = "weighted", window = 3)

Right now the above code is selecting 3 words before and after the target feature. Any possibility of setting the window to select the left side of the target feature?

Thanks for the help.

Answer 1

You could use ordered = TRUE after reversing the tokens. So:

library("quanteda")
## Package version: 3.0.0
## Unicode version: 10.0
## ICU version: 61.1
## Parallel computing: 12 of 12 threads used.
## See https://quanteda.io for tutorials and examples.

toks <- tokens(c("A D A C", "A B D E"))

fcm(toks, context = "window", window = 2, ordered = TRUE)
## Feature co-occurrence matrix of: 5 by 5 features.
##         features
## features A D C B E
##        A 1 2 1 1 0
##        D 1 0 1 0 1
##        C 0 0 0 0 0
##        B 0 1 0 0 1
##        E 0 0 0 0 0

fcm(as.tokens(lapply(toks, rev)),
  context = "window", window = 2, ordered = TRUE
)
## Feature co-occurrence matrix of: 5 by 5 features.
##         features
## features C A D E B
##        C 0 1 1 0 0
##        A 0 1 1 0 0
##        D 0 2 0 0 1
##        E 0 0 1 0 1
##        B 0 1 0 0 0

^{Created on 2021-04-12 by the reprex package (v1.0.0)}