Replace coordinates in API data character string Using for loop in R

Question

I am trying to run a for loop on the following Gage Data

nfgages<-read.csv("C:\\Users\\Jay_Oliver\\Documents\\Texas EFlow Spatial\\Missing Watersheds.csv", colClasses = c("SOURCE_FEA" = "character"))
lnfgages<-as.list(nfgages$Gage.Number)

head(nfgages)
  FID   REACHCODE SOURCE_FEA Gage.Number  POINT_Y    POINT_X
1   1 1.11302e+13    7315600     7315600 33.88263  -97.65270                                   
2   2 1.11401e+13    7331700     7331700 33.80217  -96.58093                             
3   6 1.11302e+13    7311622     7311622 33.86995  -99.94693                                     
4   7 1.11302e+13    7316200     7316200 33.70243  -96.84774                                    
5   9 1.11401e+13    7335390     7335390 33.84773  -95.55042                                       
6  10 1.11201e+13    7299200     7299200 34.57315 -100.74567                                

What I am trying to do is set up an API connection using the following coordinates, but I am running into issues when trying to replace the coordinates through the for loop. I tried placing Point_Y[i], Point_X[i] but as its a character string, it is not replacing the values but rather copying the original input over and over again producing an error.

for (i in 1:length(lnfgages)) {
data = '{  "location": [Point_Y[i], Point_x[i]],  
"snappingOn": true,  "simplify": 0.0001,  "dataSource": "nhd"}'
 }

headers = c(
  `accept` = 'application/json',
  `Authorization` = 'Token {Your API Token Here}',
  `Content-Type` = 'application/json',
  `X-CSRFToken` = '9P7k41yjWNqVtysnv8iv2KfeW4vadHih1wKZWkN41Mln249QxEZVZHwfvKcufvBO',
  'Accept-Encoding' = 'gzip'
)

# Location can be substituted with any location
data = '{  "location": [Point_Y[i], Point_x[i]],  
"snappingOn": true,  "simplify": 0.0001,  "dataSource": "nhd"}'