This is my first attempt to try R web scraping tools, for a project my daughter is working on. It concerns a data base of projects in Sao Paulo, Brazil, listed at http://outorgaonerosa.prefeitura.sp.gov.br/relatorios/RelSituacaoGeralProcessos.aspx, but spread out over 69 pages accessed through a javascript menu at the bottom of the page.
Each web page contains 3 HTML tables, of which only the last contains the relevant data. In this, only a subset of columns are of interest. I tried using the XML package as illustrated on several tutorial pages, as shown below. I have no idea how to automate this to extract these tables from multiple web pages. Is there some other package better suited to this task? Can someone help me solve this and other issues? # Goal: read the data tables contained on 69 pages generated by the link below, where # each page is generated by a javascript link in the menu of the bottom of the page. # # Each "page" contains 3 html tables, with names "Table 1", "Table 2", and the only one # of interest with the data, "grdRelSitGeralProcessos" # # From each such table, extract the following columns: #- Processo #- Endereço #- Distrito #- Area terreno (m2) #- Valor contrapartida ($) #- Area excedente (m2) # NB: All of the numeric fields use "." as comma-separator and "," as the decimal separator, # but because of this are read in as character library(XML) link <- "http://outorgaonerosa.prefeitura.sp.gov.br/relatorios/RelSituacaoGeralProcessos.aspx" saopaulo <- htmlParse(link) saopaulo.tables <- readHTMLTable(saopaulo, stringsAsFactors = FALSE) length(saopaulo.tables) # its the third table on this page we want sp.tab <- saopaulo.tables[[3]] # columns wanted wanted <- c(1, 2, 5, 7, 8, 13, 14) head(sp.tab[, wanted]) > head(sp.tab[, wanted]) Proposta Processo Endereço Distrito 1 1 2002-0.148.242-4 R. DOMINGOS LOPES DA SILVA X R. CORNÉLIO VAN CLEVE VILA ANDRADE 2 2 2003-0.129.667-3 AV. DR. JOSÉ HIGINO, 200 E 216 AGUA RASA 3 3 2003-0.065.011-2 R. ALIANÇA LIBERAL, 980 E 990 VILA LEOPOLDINA 4 4 2003-0.165.806-0 R. ALIANÇA LIBERAL, 880 E 886 VILA LEOPOLDINA 5 5 2003-0.139.053-0 R. DR. JOSÉ DE ANDRADE FIGUEIRA, 111 VILA ANDRADE 6 6 2003-0.200.692-0 R. JOSÉ DE JESUS, 66 VILA SONIA Ãrea Terreno (m2) Ãrea Excedente (m2) Valor Contrapartida (R$) 1 0,00 1.551,14 127.875,98 2 0,00 3.552,13 267.075,77 3 0,00 624,99 70.212,93 4 0,00 395,64 44.447,18 5 0,00 719,68 41.764,46 6 0,00 446,52 85.152,92 thanks, -- Michael Friendly Email: friendly AT yorku DOT ca Professor, Psychology Dept. & Chair, Quantitative Methods York University Voice: 416 736-2100 x66249 Fax: 416 736-5814 4700 Keele Street Web:http://www.datavis.ca Toronto, ONT M3J 1P3 CANADA [[alternative HTML version deleted]] ______________________________________________ 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.