DataFrame comparison methods
The DataFrame class provides methods to compare across
rows of the DataFrame, including ordering and matching. Each
DataFrame is effectively treated as a vector of rows.
## S4 method for signature 'DataFrame'
sameAsPreviousROW(x)
## S4 method for signature 'DataFrame,DataFrame'
match(x, table, nomatch = NA_integer_, incomparables = NULL, ...)
## S4 method for signature 'DataFrame'
order(..., na.last = TRUE, decreasing = FALSE, method = c("auto",
"shell", "radix"))
## S4 method for signature 'DataFrame,DataFrame'
pcompare(x, y)
## S4 method for signature 'DataFrame,DataFrame'
e1 == e2
## S4 method for signature 'DataFrame,DataFrame'
e1 <= e2The treatment of a DataFrame as a “vector of rows”
is useful in many cases, e.g., when each row is a record that needs
to be ordered or matched. The methods provided here allow the use of
all methods described in ?Vector-comparison, including
sorting, matching, de-duplication, and so on.
Careful readers will notice this behaviour differs from the usual
semantics of a data.frame, which acts as a list-like vector
of columns. This discrepancy rarely causes problems, as it is not
particularly common to compare columns of a data.frame in
the first place.
Note that a match method for DataFrame objects is
explicitly defined to avoid calling the corresponding method for
List objects, which would yield the (undesired) list-like
semantics. The same rationale is behind the explicit definition of
<= and == despite the availability of pcompare.
For sameAsPreviousROW: see sameAsPreviousROW.
For match: see match.
For order: see order.
For pcompare, == and <=: see pcompare.
Aaron Lun
# Mocking up a DataFrame.
DF <- DataFrame(
A=sample(LETTERS, 100, replace=TRUE),
B=sample(5, 100, replace=TRUE)
)
# Matching:
match(DF, DF[1:10,])
selfmatch(DF)
unique(DF)
# Ordering, alone and with other vectors:
sort(DF)
order(DF, runif(nrow(DF)))
# Parallel comparison:
DF==DF
DF==DF[1,]Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.