I'm trying to run a loop in R script on a dataframe called input. and update the column name Valid.
function myFunction(x){
Result <- x * 2
return(Result)
}
for (row in nrow(input)){
input$Valid[row] == myFunction(2)
}
output <- input
But not getting the dataframe updated. And Yes I want to do this in a loop.
There are several issues in your for loop:
nrow(input) is just a number, so you need to create a range from 1 to nrow(input), i.e., seq_len(nrow(input))== is to judge the equality, so, use <- or = for value assignmentExample
for (row in seq_len(nrow(input))){
input$Valid[row] <- myFunction(2)
}
1:nrow(...) is fragile, what if this is done with a 0-row frame (it breaks, try 1:0). Instead, I suggest seq_len(NROW(input)), as it deals correctly with the 0-row frame.seq(0) still returns [1] 1 0, which means the loop will still try to do something to two non-existent rows. Contrast with seq_len(0), which returns integer(0). (And seq_along(nrow(input)) is too similar to the OP, though here it will always operate on the first row, c.f., seq_along(100).)I was able to get it working with your suggestions:
Here is the full script I'm using : Which is using a SOAP request to validate EU vat numbers with http://ec.europa.eu/taxation_customs/vies/checkVatService.wsd
VatCheck <- function(x,z)
{
get_config_proxy <- function(url, user = NULL, pwd = NULL, verbose = FALSE, auth = "basic") {
# curl::ie_get_proxy_for_url wants a scheme - either way it don't work
if(is.null(httr::parse_url(url)$scheme)) {
if (verbose) message("No scheme provided. assume HTTP")
url <- modify_url(url, scheme = "http")
}
# get the proxy url if needed
proxy_url <- curl::ie_get_proxy_for_url(url)
# return blank config if no proxy required
if(is.null(proxy_url)) {
if(verbose) message("No proxy")
return(httr::config())
}
if(verbose) message("Proxy found")
# Otherwise configure the proxy / user and password are needed
# return a config object for use with httr
proxy_config <- httr::use_proxy(url = proxy_url, auth = auth)
}
body = sprintf("<soapenv:Envelope xmlns:soapenv='http://schemas.xmlsoap.org/soap/envelope/' xmlns:urn='urn:ec.europa.eu:taxud:vies:services:checkVat:types'>
<soapenv:Body>
<urn:checkVat xmlns='urn:ec.europa.eu:taxud:vies:services:checkVat:types'>
<urn:countryCode>%s</urn:countryCode>
<urn:vatNumber>%s</urn:vatNumber>
</urn:checkVat>
</soapenv:Body>
</soapenv:Envelope>",x,z)
url <- "http://ec.europa.eu/taxation_customs/vies/services/checkVatService"
# No proxy configured so we get a timeout from curl fetch
# req <- GET(url)
# we configure the proxy giving interactively user and password
config_proxy <- get_config_proxy(url)
# we make a GET using the config
x <- with_config(config_proxy, POST(url, body=body))
req<-toString(content(x)) # we get 200. it works!
req
}
for(i in 1:nrow(input)) {
input[i, "Valid"] <- VatCheck(x = toString(input[i, "Column1"]) , z= toString(input[i, "Colum2"]))
}
output <- input