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Posted to github@arrow.apache.org by GitBox <gi...@apache.org> on 2022/11/18 14:35:38 UTC
[GitHub] [arrow-nanoarrow] paleolimbot commented on a diff in pull request #65: [R] Complete ptype inferences and array conversions
paleolimbot commented on code in PR #65:
URL: https://github.com/apache/arrow-nanoarrow/pull/65#discussion_r1026511358
##########
r/src/convert.c:
##########
@@ -0,0 +1,483 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+#define R_NO_REMAP
+#include <R.h>
+#include <Rinternals.h>
+
+#include "nanoarrow.h"
+
+#include "array.h"
+#include "convert.h"
+#include "materialize.h"
+#include "schema.h"
+
+static R_xlen_t nanoarrow_vec_size(SEXP vec_sexp, struct PTypeView* ptype_view) {
+ if (ptype_view->vector_type == VECTOR_TYPE_DATA_FRAME) {
+ if (Rf_length(vec_sexp) > 0) {
+ // Avoid materializing the row.names if we can
+ return Rf_xlength(VECTOR_ELT(vec_sexp, 0));
+ } else {
+ return Rf_xlength(Rf_getAttrib(vec_sexp, R_RowNamesSymbol));
Review Comment:
Thanks! I played with this a little bit and if I go this route I have to implement inspecting for `c(NA, nrow)`, `c(NA, -nrow)` myself and I'm a little worried I will mess this up. It looks like rownames are sufficiently ALTREP even when expanded in recent R (although I don't know how far back this goes) such that computing the length shouldn't be an expensive operation?
``` r
df <- nanoarrow:::new_data_frame(x = 1:1e9, 1e9)
.Internal(inspect(df))
#> @141c96758 13 INTSXP g0c0 [OBJ,REF(2),ATT] wrapper [srt=-2147483648,no_na=0]
#> @141c93060 13 INTSXP g0c0 [REF(65535)] 1 : 1000000000 (compact)
#> ATTRIB:
#> @141c96720 02 LISTSXP g0c0 [REF(1)]
#> TAG: @15780c9f0 01 SYMSXP g1c0 [MARK,REF(65535),LCK,gp=0x4000] "row.names" (has value)
#> @141d29098 13 INTSXP g0c1 [REF(1)] (len=2, tl=0) -2147483648,1000000000
#> TAG: @15780d1d0 01 SYMSXP g1c0 [MARK,REF(38209),LCK,gp=0x6000] "class" (has value)
#> @141d29290 16 STRSXP g0c1 [REF(65535)] (len=1, tl=0)
#> @157891e08 09 CHARSXP g1c2 [MARK,REF(576),gp=0x61,ATT] [ASCII] [cached] "data.frame"
str(attr(df, "row.names"))
#> int [1:1000000000] 1 2 3 4 5 6 7 8 9 10 ...
bench::mark(attr(df, "row.names"))
#> # A tibble: 1 × 6
#> expression min median `itr/sec` mem_alloc `gc/sec`
#> <bch:expr> <bch:tm> <bch:tm> <dbl> <bch:byt> <dbl>
#> 1 attr(df, "row.names") 41ns 82ns 8860040. 0B 0
```
<sup>Created on 2022-11-18 with [reprex v2.0.2](https://reprex.tidyverse.org)</sup>
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