获取错误：一元运算符的参数无效

Question

最初，除了forecasttext <- 0之外，我在下面写了所有代码但是我一直收到错误：找不到对象。所以我将forecastext定义为0.

现在我遇到了错误：-html_text（forecasthtml）出错：一元运算符的参数无效

任何解决方案？

install.packages("rvest")
library (rvest)

forecasttext <- 0

weatherlink <- read_html("http://forecast.weather.gov/MapClick.php?
lat=36.11479000000003&lon=-115.17280999999997#.WXfQRdPytE4")

forecasthtml <- html_node(weatherlink, "#detailed-forecast div:nth-
                          child(1) :nth-child(1)")

forecasttext < - html_text (forecasthtml)

Answer 1

forecasttext < - html_text (forecasthtml) 

应该是

forecasttext <- html_text (forecasthtml)