rlatitude-longitudegoogle-latitude

How to convert Degree Decimal Minutes (DDM) to Degree Decimals in R dataset?


I have a data set that looks like this

        lat_deg lat_min long_deg long_min
site 1     44     4.971    80     27.934
site 2
site 3
site 4
site 5


site <- c(1,2,3)
lat_deg <- c(44,44,44)
lat_min <- c(4.971, 4.977, 4.986)
long_deg <- c(80,80,80)
long_min <- c(27.934, 27.977, 27.986)
df <- data.frame(site, lat_deg, lat_min, long_deg, long_min)

How do I convert this into degree decimal only? All my lats are in N and longs in W, so I'm not too worried except the final sign should be correct. Additionally, will I be able to calculate altitude from here?

Note: All other questions on SO focus on DMS to DD. This question has not been asked before.


Solution

  • Based on the data given, here is a approach using dplyr:

    df %>%
      mutate(lat = lat_deg + lat_min/60,
             long = long_deg + long_min/60)
    

    returns

      site lat_deg lat_min long_deg long_min      lat     long
    1    1      44   4.971       80   27.934 44.08285 80.46557
    2    2      44   4.977       80   27.977 44.08295 80.46628
    3    3      44   4.986       80   27.986 44.08310 80.46643
    

    or simply

    df$lat <- df$lat_deg + df$lat_min/60
    df$long <- df$long_deg + df$long_min/60