Hi, I have mined XML extensively with R before now, but my xpath chops seem to be regressing recently. I know that I can roll up my sleeves and search through the child nodes of the root, but I can't noodle out why using the xpath description returns an empty nodeset.
Any suggestions and nudges most welcome. ### START library(xml2) library(httr) library(magrittr) daymet_uri <- "https://thredds.daac.ornl.gov/thredds/catalog/ornldaac/1328/catalog.xml"; # run the following to show the node in a browser # httr::BROWSE(daymet_uri) daymet <- httr::GET(daymet_uri) %>% httr::content(type = "text/xml", encoding = "UTF-8") # list the children "service" and "dataset" daymet %>% xml2::xml_children() #{xml_nodeset (2)} #[1] <service name="all" serviceType="Compound" base="">\n <service name="odap" #serviceTyp ... #[2] <dataset name="Daymet: Daily Surface Weather Data on a 1-km Grid for North America, Ve ... # find all descendants of node name "dataset" # # according to this tutorial we should find 'dataset' # https://www.w3schools.com/xml/xpath_syntax.asp daymet %>% xml2::xml_find_all(xpath = "//dataset") # {xml_nodeset (0)} # I have also tried every other xpath combination I think of e.g. # ".//dataset", "./dataset", "/dataset" and "dataset" # They each yield an empty nodeset ### END > sessionInfo() R version 3.5.1 (2018-07-02) Platform: x86_64-redhat-linux-gnu (64-bit) Running under: CentOS Linux 7 (Core) Matrix products: default BLAS/LAPACK: /usr/lib64/R/lib/libRblas.so locale: [1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C [3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8 [5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8 [7] LC_PAPER=en_US.UTF-8 LC_NAME=C [9] LC_ADDRESS=C LC_TELEPHONE=C [11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C attached base packages: [1] stats graphics grDevices utils datasets methods [7] base other attached packages: [1] magrittr_1.5 httr_1.4.1 xml2_1.2.2 loaded via a namespace (and not attached): [1] compiler_3.5.1 R6_2.4.0 tools_3.5.1 curl_4.2 [5] yaml_2.2.0 Rcpp_1.0.3 Thanks, Ben Ben Tupper Bigelow Laboratory for Ocean Sciences 60 Bigelow Drive, P.O. Box 380 East Boothbay, Maine 04544 http://www.bigelow.org Ecological Forecasting: https://eco.bigelow.org/ ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
