CODEWITHSUNDEEP
r
KT_1
KT_1

Reputation: 8494

Converting latitude and longitude

The following data frame represents latitude and longitude decimal coordinates. I wish to using + and - to show whether the decimal degrees are North, South, East or West (in the latitude and longitude column).

So, latitude would be positive if the decimal degrees were N. ... the latitude would be negative if the decimal degrees were S. ... the longitude would be positive if the decimal degrees were E and the longitude would be negative if the decimal degrees were W.

a <- c(1:3)
Lat <- c(54.5, 55.2, 10.1)
NS <- c("N","N","S")
Long <- c(1.2, 0.5, 1.3)
EW <- c("W","E","W")
df1 <- data.frame(a,Lat,NS,Long,EW)

How would I do this in R? Any advice would be much appreciated.

Upvotes: 4

Views: 2609

Answers (3)

plannapus
plannapus

Reputation: 18759

Quite simply with ifelse:

df2 <- data.frame(a=df1$a, Lat=ifelse(df1$NS=="N", df1$Lat, -1*df1$Lat), 
                           Long=ifelse(df1$EW=="E", df1$Long, -1*df1$Long))

df2
  a   Lat  Long
1 1  54.5 -1.2
2 2  55.2  0.5
3 3 -10.1 -1.3

Upvotes: 0

lucasddaniel
lucasddaniel

Reputation: 1789

See NMEA conversion: http://www.nmea.org/ but, you can do it in a for() method to get one by one position

Upvotes: 0

Andrie
Andrie

Reputation: 179558

Use ifelse:

df1 <- within(df1, {
             Lat <- ifelse(NS=="N", Lat, -Lat)
             Long <- ifelse(EW=="E", Long, -Long)
})

df1
  a   Lat NS Long EW
1 1  54.5  N -1.2  W
2 2  55.2  N  0.5  E
3 3 -10.1  S -1.3  W

I use within() to reduce the amount of typing.

Upvotes: 5

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