CODEWITHSUNDEEP
rgeospatialcategorical-data
Marie-Christine Rufener
Marie-Christine Rufener

Reputation: 119

Setting categorical variable based on georreferenced data

I'm having a little problem that I can't resolve by myself.

I have a data frame containing some environmental information as well as the latitude and longitude for each sample stations. I want to divide my study area into 4 smaller areas (see the image below), whose information I want to include into a new column into my hole data frame. That is, my new column should be a factor with 4 levels, each of them corresponding to specific geolocation ranges based on each area limits.

enter image description here

As example, let say that my Area 1 is defined as being all sample stations located between longitudes (-10.4 to -10.6) and latitudes (-37 to -36.2.). Thus, at the end I want to have a data frame like this:

Variable 1   Variable 2  Latitude  Longitude  Area  
0.98          1.5         -10.2      -37.5     1
0.74          0.9         -10.1      -37.5     1
0.58          0.7         -11.7      -36.8     3
0.94          1.2         -11.9      -37.5     4

and so on. Can anyone help me to solve my problem?

Upvotes: 1

Views: 111

Answers (1)

JACKY88
JACKY88

Reputation: 3557

If the intervals are solely determined by Latitude, then you could use the following.

> Var1 <- runif(100)
> Var2 <- runif(100)
> Latitude <- runif(100, -13.0, -10.0)
> Longitude <- runif(100, -38.0, -36.0)
> 
> dat <- data.frame(Var1, Var2, Latitude, Longitude)
> 
> Area <- as.numeric(cut(dat$Latitude, breaks = c(-13.0, -12.0, -11.0, -10.0)))
> 
> dat <- data.frame(dat, Area)
> dat
           Var1       Var2  Latitude Longitude Area
1   0.655301728 0.14144585 -10.48851 -37.96152    3
2   0.107591891 0.72131348 -11.75188 -36.05489    2
3   0.639967329 0.98282855 -10.76784 -36.01176    3
4   0.295014765 0.31968068 -11.99204 -37.48354    2
5   0.373011497 0.21168608 -11.62501 -36.37215    2
6   0.802966559 0.69812115 -11.56078 -37.09359    2
7   0.013607591 0.47285961 -10.95633 -36.06122    3
8   0.309604142 0.14035926 -10.94194 -37.61688    3
9   0.066620024 0.15386860 -12.26123 -36.84730    1
10  0.066227174 0.70843535 -12.06751 -36.44342    1
11  0.551767865 0.60483061 -12.78234 -36.23624    1
12  0.770809846 0.80973319 -10.47946 -37.97104    3
13  0.909879222 0.04641956 -11.18606 -36.91503    2

Or you can use 

Area <- as.numeric(cut(dat$Latitude, breaks = 4))

to have 4 intervals.

Upvotes: 1

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