Plotting lines in R between coordinate pairs based on summed quantities in a dataset. How do I get these lines to appear using Leaflet and geospheres

Question

See the code below. Currently I'm getting a clean run through but the output is a map with no lines and >50 warnings

pal <- colorRampPalette(c("#f2f2f2", "red"))
colors <- pal(100)
maxsum <- max(Szn21$`Sum of QTY`)
for (j in 1:length(Szn21$MKT.COO)) 
  {

   colindex <- round( (Szn21$Sum.of.QTY[j] / maxsum) * length(colors) )

   inter <- gcIntermediate(c(Szn21$Mkt_longit[j], Szn21$Mkt_Lat[j]),
                      c(Szn21$Coo_longit[j], Szn21$Coo_Lat[j]),
                      sp=TRUE, n=50, addStartEnd=TRUE)
  leaflet() %>% 
    addTiles() %>%
    addPolylines(data = inter, col=colindex, opacity = 0.2) 
}

Answer 1

等待大神解答