[Rcpp-devel] Help reading libzma file

[Dirk Eddelbuettel]

On 23 June 2022 at 10:05, Serguei Sokol wrote:
| Le 23/06/2022 à 04:07, Roberto Spadim a écrit :
| > Hi folks
| > 
| > I have a .xz file and need to read it and "convert" to a DataFrame using 
| > Rcpp if possible.
| > 
| > But... I'm with a problem (first time testing this) using liblzma with 
| > Rcpp, I already know how to do this with CMakeLists.txt, but I don't 
| > know how to do with RCpp
| > 
| > Anyone have an idea?
| You have to use Makevars file, either in src/ or in $HOME/.R/ dir.
| In this file you have to add something like:
| 
|    PKG_CPPFLAGS += -I<dir_where_lzma.h_leaves>
|    PKG_LDFLAGS += -L<dir_where_liblzma.so_lives> -llzma
| 
| To make this solution portable, you can want to use configure script 
| which usage is described in WRE 
| https://cran.r-project.org/doc/manuals/r-release/R-exts.html#Configure-and-cleanup
| 
| Best,
| Serguei.
| 
| > 
| > Output from compile time:
| > 
| >  > sourceCpp("D:/Trabalho/FTDB-R/FTDB/src/ftdbR.cpp")

And you want to look into using a package, not `sourceCpp()` which is
designed for more one-off interactive work.

You can start a package with the `Rcpp.package.skeleton()` function, and then
add a src/Makevars as correctly suggested by Serguei.  There are also many
example Rcpp on CRAN, GitHub and other places to look at.  The `qs` and `fst`
packages both cover compression too (but do a lot more...), I can't right now
think of a simpler package adding just one compressor but there may well be one.

Regards, Dirk

| > /mingw64/bin/g++ -std=gnu++11  -I"C:/PROGRA~1/R/R-41~1.2/include" 
| > -DNDEBUG   -I"C:/Users/rspadim/Documents/R/win-library/4.1/Rcpp/include" 
| > -I"D:/Trabalho/FTDB-R/FTDB/src" -I"D:/Trabalho/FTDB-R/FTDB/inst/include" 
| >         -O2 -Wall  -mfpmath=sse -msse2 -mstackrealign  -c 
| > D:/Trabalho/FTDB-R/FTDB/src/xz/xz/decode.cpp -o 
| > D:/Trabalho/FTDB-R/FTDB/src/xz/xz/decode.o
| > D:/Trabalho/FTDB-R/FTDB/src/xz/xz/decode.cpp:5:10: fatal error: lzma.h: 
| > No such file or directory
| >   #include <lzma.h>
| >            ^~~~~~~~
| > compilation terminated.
| > make: *** [C:/PROGRA~1/R/R-41~1.2/etc/x64/Makeconf:245: 
| > D:/Trabalho/FTDB-R/FTDB/src/xz/xz/decode.o] Error 1
| > Error in sourceCpp("D:/Trabalho/FTDB-R/FTDB/src/ftdbR.cpp") :
| >    Error 1 occurred building shared library.
| > In addition: Warning message:
| > In normalizePath(path.expand(path), winslash, mustWork) :
| >    path[1]="D:/Trabalho/FTDB-R/FTDB/src/../inst/include": O sistema não 
| > pode encontrar o caminho especificado
| > 
| > 
| > _______________________________________________
| > Rcpp-devel mailing list
| > Rcpp-devel at lists.r-forge.r-project.org
| > https://lists.r-forge.r-project.org/cgi-bin/mailman/listinfo/rcpp-devel
| 
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-- 
dirk.eddelbuettel.com | @eddelbuettel | edd at debian.org