Call a function multiple times with different argument for date

Question

I need to call the same function 10 times, each time with a different year for the end date argument. For example, the end date needs to start as "2011-01-01", then "2012-01-01", then "2013-01-01", etc. How do I loop this function but change the one argument until the last end date is "2020-01-01"?

VI <- mt_subset(product = "MOD13Q1",
                band = "250m_16_days_NDVI",
                lon = 28.5826,
                lat = 1.4368,
                start = "2010-01-01",
                end = "2011-01-01",
                km_lr = 20,
                km_ab = 20,
                site_name = "Ituri test",
                internal = TRUE,
                progress = TRUE)

Answer 1

You just have to create a vector of years to iterate on and then assign the value of mt_subset to different objects

# first create the vector of the years
years = c()
for(i in 2011:2020) { 
years = c(years, sprintf("%s-01-01", i))
  }
print(years) # check the vector


# iterate
for(i in 1:(length(years) - 1)) { 
  nam = paste("VI", i, sep = "_") # create names for the objects
  assign(nam) <- mt_subset(product = "MOD13Q1",
                  band = "250m_16_days_NDVI",
                  lon = 28.5826,
                  lat = 1.4368,
                  start = years[i],
                  end = years[i + 1],
                  km_lr = 20,
                  km_ab = 20,
                  site_name = "Ituri test",
                  internal = TRUE,
                  progress = TRUE)
 
}