Comparison and order proxySource:
vec_proxy_order() return proxy objects, i.e.
an atomic vector or data frame of atomic vectors.
The default method of
vec_proxy_compare() assumes that all classes built
on top of atomic vectors or records are comparable. Internally the default
vec_proxy_equal(). If your class is not comparable, you will need
to provide a
vec_proxy_compare() method that throws an error.
The behavior of
vec_proxy_order() is identical to
with the exception of lists. Lists are not comparable, as comparing
elements of different types is undefined. However, to allow ordering of
data frames containing list-columns, the ordering proxy of a list is
generated as an integer vector that can be used to order list elements
by first appearance.
If a class implements a
vec_proxy_compare() method, it usually doesn't need
to provide a
vec_proxy_order() method, because the latter is implemented
by forwarding to
vec_proxy_compare() by default. Classes inheriting from
list are an exception: due to the default
vec_proxy_order() should be provided for such
classes (with identical implementations) to avoid mismatches between
comparison and sorting.
vec_proxy_equal()called by default in
vec_proxy_compare()called by default in
If the proxy for
x is a data frame, the proxy function is automatically
recursively applied on all columns as well. After applying the proxy
recursively, if there are any data frame columns present in the proxy, then
they are unpacked. Finally, if the resulting data frame only has a single
column, then it is unwrapped and a vector is returned as the proxy.
# Lists are not comparable x <- list(1:2, 1, 1:2, 3) try(vec_compare(x, x)) #> Error in vec_proxy_compare(x = x) : #> `vec_proxy_compare.list()` not supported. # But lists are orderable by first appearance to allow for # ordering data frames with list-cols df <- new_data_frame(list(x = x)) vec_sort(df) #> x #> 1 1, 2 #> 2 1, 2 #> 3 1 #> 4 3