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url <- "https://www.data.jma.go.jp/obd/stats/etrn/view/available_table.php?prec_no=44&block_no=47662" |
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suppressMessages({ |
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if (!requireNamespace("rvest", quietly = TRUE) || |
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!requireNamespace("xml2", quietly = TRUE)) { |
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stop("Missing packages: please install 'rvest' and 'xml2'.") |
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} |
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}) |
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doc <- xml2::read_html(url) |
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tables <- rvest::html_table(doc, fill = TRUE) |
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start_years <- c() |
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for (tbl in tables) { |
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if (nrow(tbl) == 0) { |
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next |
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} |
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name_norm <- tolower(gsub("\\s+", " ", names(tbl))) |
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start_cols <- which(grepl("start", name_norm)) |
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if (length(start_cols) == 0) { |
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next |
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} |
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for (idx in start_cols) { |
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values <- suppressWarnings(as.numeric(gsub("[^0-9]", "", tbl[[idx]]))) |
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values <- values[!is.na(values)] |
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start_years <- c(start_years, values) |
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} |
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} |
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if (length(start_years) == 0) { |
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stop("No start year values found in tables.") |
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} |
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cat(min(start_years), "\n") |
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