I try to using rvest package to scrape a table:
library(rvest)
x <- read_html ("http://www.jcb.jp/rate/usd04182016.html")
x %>% html_node(".CSVTable") %>% html_table
Url elements look likes:
<table class="CSVTable">
<tbody>...</tbody>
<tbody class>...</tbody>
</table>
Why I occur the error "No matches"?
You're in luck (kind of). The site uses dynamic XHR requests to make that table, but said request is also a CSV file.
library(rvest)
library(stringr)
pg <- read_html("http://www.jcb.jp/rate/usd04182016.html")
# the <script> tag that does the dynamic loading is in position 6 of the
# list of <script> tags
fil <- str_match(html_text(html_nodes(pg, "script")[6]), "(/uploads/[[:digit:]]+\\.csv)")[,2]
df <- read.csv(sprintf("http://www.jcb.jp%s", fil), header=FALSE, stringsAsFactors=FALSE)
df <- setNames(df[,3:6], c("buy", "mid", "sell", "symbol"))
head(df)
## buy mid sell symbol
## 1 3.6735 3.6736 3.6737 AED
## 2 68.2700 69.0700 69.8700 AFN
## 3 122.3300 122.6300 122.9300 ALL
## 4 479.5000 481.0000 482.5000 AMD
## 5 1.7710 1.8110 1.8510 ANG
## 6 165.0600 165.3100 165.5600 AOA
But, that also means you can just get the CSV directly:
read.csv("http://www.jcb.jp/uploads/20160418.csv")
(just format the date properly in your requests).
?html_table- "Parse an html table...".Then tryx %>% html_table. You see that the table you're seeing on the page can't be parsed byhtml_table