r - 使用 R 抓取网站的 Tableau 仪表板
问题描述
我正在尝试从该站点的密苏里州 COVID 人口统计数据中抓取数据并将其放入 RStudio。另外,这是我从 HTML 中找到的 Tableau URL:https ://results.mo.gov/t/COVID19/views/Demographics/Public-Demographics?:embed=y&:showVizHome=no&:host_url=https%3A% 2F%2Fresults.mo.gov%2F&:embed_code_version=3&:tabs=no&:toolbar=no&:showAppBanner=false&:%E2%80%98iframeSizedToWindow%E2%80%99=%E2%80%98true%E2%80% 99&:dataDetails=no&:display_spinner=no&:loadOrderID=0
我一直在这里使用这个论坛来指导如何将公共画面仪表板刮到 R 中,但它似乎没有为我的数据框提供任何行或列。
这是我尝试重新创建的代码:
library(rvest)
library(rjson)
library(httr)
library(stringr)
tableauHost <- "https://results.mo.gov"
url <- httr::modify_url(tableauHost,
path = "/t/COVID19/views/Demographics/Public-Demographics",
query = list(":embed" = "y",
":showVizHome" = "no",
":host_url" = "https://results.mo.gov/",
":embed_code_version" = 3,
":tabs" = "no",
":toolbar" = "no",
":showAppBanner" = "false",
":'iframeSizedToWindow'" = "'true'",
":dataDetails" = "no",
":display_spinner" = "no",
":loadOrderID" = 0)
)
body <- read_html(url)
data <- body %>%
html_nodes("textarea#tsConfigContainer") %>%
html_text()
json <- fromJSON(data)
url <- modify_url(tableauHost, path = paste(json$vizql_root, "/bootstrapSession/sessions/", json$sessionid, sep =""))
resp <- POST(url, body = list(sheet_id = json$sheetId), encode = "form")
data <- content(resp, "text")
extract <- str_match(data, "\\d+;(\\{.*\\})\\d+;(\\{.*\\})")
info <- fromJSON(extract[1,1])
data <- fromJSON(extract[1,3])
worksheet <- "+ PCR by age"
columnsData <- data$secondaryInfo$presModelMap$vizData$presModelHolder$genPresModelMapPresModel$presModelMap[[worksheet]]$presModelHolder$genVizDataPresModel$paneColumnsData
i <- 1
result <- list();
for(t in columnsData$vizDataColumns){
if (is.null(t[["localBaseColumnName"]]) == FALSE) {
result[[i]] <- list(
localBaseColumnName = t[["localBaseColumnName"]],
valueIndices = columnsData$paneColumnsList[[t$paneIndices + 1]]$vizPaneColumns[[t$columnIndices + 1]]$valueIndices,
aliasIndices = columnsData$paneColumnsList[[t$paneIndices + 1]]$vizPaneColumns[[t$columnIndices + 1]]$aliasIndices,
dataType = t[["dataType"]],
stringsAsFactors = FALSE
)
i <- i + 1
}
}
dataFull = data$secondaryInfo$presModelMap$dataDictionary$presModelHolder$genDataDictionaryPresModel$dataSegments[["0"]]$dataColumns
buildOffset = function(x){
return(if(x>=0) 0 else -1)
}
data_index <- 1
name_index <- 1
frameData <- list();
frameNames <- c()
for(t in dataFull) {
for(index in result) {
if (t$dataType == "cstring"){
if (length(index$valueIndices) > 0) {
j <- 1
vector <- character(length(index$valueIndices))
for (it in index$valueIndices){
vector[j] <- t$dataValues[abs(it)+1]
j <- j + 1
}
frameData[[data_index]] <- vector
frameNames[[name_index]] <- paste(index$localBaseColumnName, "value", sep="-")
data_index <- data_index + 1
name_index <- name_index + 1
}
if (length(index$aliasIndices) > 0) {
j <- 1
vector <- character(length(index$aliasIndices))
for (it in index$aliasIndices){
vector[j] <- t$dataValues[abs(it) + buildOffset(it) + 1]
j <- j + 1
}
frameData[[data_index]] <- vector
frameNames[[name_index]] <- paste(index$localBaseColumnName, "alias", sep="-")
data_index <- data_index + 1
name_index <- name_index + 1
}
}
}
}
columnToKeep = c('[Student Aid Program Type]-value','[Student Aid Program]-value', '[:Measure Names]-alias', '[Multiple Values]-alias')
df <- NULL
for(i in 1:length(frameNames)){
if (frameNames[i] %in% columnToKeep){
df[frameNames[i]] <- frameData[i]
}
}
options(width = 1200) #for readability
df <- as.data.frame(df, stringsAsFactors = FALSE)
print(df)
但它只是给我这个作为输出
print(df)
data frame with 0 columns and 0 rows
我知道columnToKeep
我们为数据框定义列的部分与我正在寻找的数据不匹配,那么不正确的列数会影响这一点吗?我一直在尝试破译原始代码并使用密苏里 COVID 的仪表板实现它,但每次看到它都让我非常困惑。对此的任何帮助将不胜感激!
解决方案
问题是它需要以aliasIndices
不同的方式处理。流程如下:
选择下面的工作表
data$secondaryInfo$presModelMap$vizData$presModelHolder$genPresModelMapPresModel$presModelMap
下presModelHolder$genVizDataPresModel$paneColumnsData
:
- 获取下的所有列
vizDataColumns
,注意fieldCaption
作为列名 - 注意所有列的
paneIndices
andcolumnIndices
- 对于每一列,在 下
paneColumnsList
,将行分配给指定的 columnIndices 以及在vizPaneColumns
which 下给出的值valueIndices
以及aliasIndices
哪些是字典中实际数据的索引
在字典中(在 下data$secondaryInfo$presModelMap$dataDictionary$presModelHolder$genDataDictionaryPresModel$dataSegments
),您拥有完整的数据。您只需要匹配您之前提取的索引。为了匹配这些索引,您需要让dataType
列的 知道要在字典中选择哪个对象,然后:
valueIndices
仅在列表中分配索引- 对于
aliasIndices
,如果值 > 0 分配索引,如果它是负数,则将列表中的索引与dataType
“cstring”匹配
我不确定这个算法是否适用于所有画面数据,但对于我测试过的一些数据来说效果很好:
library(rvest)
library(rjson)
library(httr)
library(stringr)
#replace the hostname and the path if necessary
host_url <- "https://results.mo.gov"
path <- "/t/COVID19/views/Demographics/Public-Demographics"
body <- read_html(modify_url(host_url,
path = path,
query = list(":embed" = "y",":showVizHome" = "no")
))
data <- body %>%
html_nodes("textarea#tsConfigContainer") %>%
html_text()
json <- fromJSON(data)
url <- modify_url(host_url, path = paste(json$vizql_root, "/bootstrapSession/sessions/", json$sessionid, sep =""))
resp <- POST(url, body = list(sheet_id = json$sheetId), encode = "form")
data <- content(resp, "text")
extract <- str_match(data, "\\d+;(\\{.*\\})\\d+;(\\{.*\\})")
info <- fromJSON(extract[1,1])
data <- fromJSON(extract[1,3])
worksheets = names(data$secondaryInfo$presModelMap$vizData$presModelHolder$genPresModelMapPresModel$presModelMap)
for(i in 1:length(worksheets)){
print(paste("[",i,"] ",worksheets[i], sep=""))
}
selected <- readline(prompt="select worksheet by index: ");
worksheet <- worksheets[as.integer(selected)]
print(paste("you selected :", worksheet, sep=" "))
columnsData <- data$secondaryInfo$presModelMap$vizData$presModelHolder$genPresModelMapPresModel$presModelMap[[worksheet]]$presModelHolder$genVizDataPresModel$paneColumnsData
i <- 1
result <- list();
for(t in columnsData$vizDataColumns){
if (is.null(t[["fieldCaption"]]) == FALSE) {
paneIndex <- t$paneIndices
columnIndex <- t$columnIndices
if (length(t$paneIndices) > 1){
paneIndex <- t$paneIndices[1]
}
if (length(t$columnIndices) > 1){
columnIndex <- t$columnIndices[1]
}
result[[i]] <- list(
fieldCaption = t[["fieldCaption"]],
valueIndices = columnsData$paneColumnsList[[paneIndex + 1]]$vizPaneColumns[[columnIndex + 1]]$valueIndices,
aliasIndices = columnsData$paneColumnsList[[paneIndex + 1]]$vizPaneColumns[[columnIndex + 1]]$aliasIndices,
dataType = t[["dataType"]],
stringsAsFactors = FALSE
)
i <- i + 1
}
}
dataFull = data$secondaryInfo$presModelMap$dataDictionary$presModelHolder$genDataDictionaryPresModel$dataSegments[["0"]]$dataColumns
cstring <- list();
for(t in dataFull) {
if(t$dataType == "cstring"){
cstring <- t
break
}
}
data_index <- 1
name_index <- 1
frameData <- list()
frameNames <- c()
for(t in dataFull) {
for(index in result) {
if (t$dataType == index["dataType"]){
if (length(index$valueIndices) > 0) {
j <- 1
vector <- character(length(index$valueIndices))
for (it in index$valueIndices){
vector[j] <- t$dataValues[it+1]
j <- j + 1
}
frameData[[data_index]] <- vector
frameNames[[name_index]] <- paste(index$fieldCaption, "value", sep="-")
data_index <- data_index + 1
name_index <- name_index + 1
}
if (length(index$aliasIndices) > 0) {
j <- 1
vector <- character(length(index$aliasIndices))
for (it in index$aliasIndices){
if (it >= 0){
vector[j] <- t$dataValues[it+1]
} else {
vector[j] <- cstring$dataValues[abs(it)]
}
j <- j + 1
}
frameData[[data_index]] <- vector
frameNames[[name_index]] <- paste(index$fieldCaption, "alias", sep="-")
data_index <- data_index + 1
name_index <- name_index + 1
}
}
}
}
df <- NULL
lengthList <- c()
for(i in 1:length(frameNames)){
lengthList[i] <- length(frameData[[i]])
}
max <- max(lengthList)
for(i in 1:length(frameNames)){
if (length(frameData[[i]]) < max){
len <- length(frameData[[i]])
frameData[[i]][(len+1):max]<-""
}
df[frameNames[[i]]] <- frameData[i]
}
options(width = 1200)
df <- as.data.frame(df, stringsAsFactors = FALSE)
print(df)
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