pvar | R Documentation |
This function checks for each variable of a panel if it varies cross-sectionally and over time.
pvar(x, ...) ## S3 method for class 'matrix' pvar(x, index = NULL, ...) ## S3 method for class 'data.frame' pvar(x, index = NULL, ...) ## S3 method for class 'pdata.frame' pvar(x, ...) ## S3 method for class 'pseries' pvar(x, ...) ## S3 method for class 'pvar' print(x, ...)
x |
a |
... |
further arguments. |
index |
see |
For (p)data.frame and matrix interface: All-NA
columns are removed
prior to calculation of variation due to coercing to pdata.frame
first.
An object of class pvar
containing the following
elements:
id.variation |
a logical vector with |
time.variation |
a logical vector with |
id.variation_anyNA |
a logical vector with |
time.variation_anyNA |
a logical vector with |
pvar
can be time consuming for “big” panels. As a fast alternative
collapse::varying()
from package collapse could be used.
Yves Croissant
pdim()
to check the dimensions of a 'pdata.frame' (and
other objects),
# Gasoline contains two variables which are individual and time # indexes and are the first two variables data("Gasoline", package = "plm") pvar(Gasoline) # Hedonic is an unbalanced panel, townid is the individual index; # the drop.index argument is passed to pdata.frame data("Hedonic", package = "plm") pvar(Hedonic, "townid", drop.index = TRUE) # same using pdata.frame Hed <- pdata.frame(Hedonic, "townid", drop.index = TRUE) pvar(Hed) # Gasoline with pvar's matrix interface Gasoline_mat <- as.matrix(Gasoline) pvar(Gasoline_mat) pvar(Gasoline_mat, index=c("country", "year"))
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