Delete identical objects

Question

I would like to detect all duplicates of coordinates of an object, which means that I want to keep one of every kind, but mark all the other ones. If I try:

for(bb in 1:nrow(Cons)){
  for(cc in 1:nrow(Cons)){
    if(identical(Cons$lat[bb], Cons$lat[cc])&& identical(Cons$lng[bb], Cons$lng[cc])&& !identical(bb,cc)){
      Cons$X[bb] <- NA
    }
  }
}

Then I get every pair of coordinates marked. Any ideas how I can keep the first one?

you can also use `unique` if you wanted the identical objects removed — manotheshark, Jan 10 '17 at 16:19
I have read both entries, but I do not get how to compare to values. They do not accept && — Laura94, Jan 10 '17 at 16:49
You can just create a new column like: `Cons$duplicated <- duplicated(subset(Cons,select = c("lat","lng")))`. — raymkchow, Jan 10 '17 at 17:08
please provide a reproducible example: http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example — timat, Jan 10 '17 at 17:09

gfgm · Answer 1 · 2017-01-10T17:30:43.123

As the comments noted this can be done with the duplicated function. Here is a reproducible example and solution:

# generate some data
# set.seed to make reproducible
set.seed(10)
lat.df <- data.frame(item=1:100, 
    lat=round(runif(100),1), 
    lon=round(runif(100),1))

    head(lat.df)
   item lat lon
1    1 0.5 0.3
2    2 0.3 0.1
3    3 0.4 0.4
4    4 0.7 0.4
5    5 0.1 0.9
6    6 0.2 0.9

If we call the duplicated function on the lat/lon columns it will give us a vector of TRUE/FALSE corresponding to whether the row has a duplicate. We can use this TRUE/FALSE vector to subset our dataframe to only the unique entries:

lat.df.unique <- lat.df[!duplicated(lat.df[,c("lat","lon")]),]

# Check dimensions of unique data.frame to see if we have removed dups
dim(lat.df.unique)
[1] 69  3

score 0 · Answer 2 · answered Jan 10 '17 at 17:32

0

In dplyr, you can do this:

library(dyplr)
Cons %>% distinct(lat, lng)

answered Jan 10 '17 at 17:32

s-heins

679
1
8
20

score 0 · Answer 3 · answered Jan 10 '17 at 21:58

0

This is a pretty easy way to do it.

library(data.table)
setDT(Cons)
Cons = unique(Cons, by = c("lat","lng"))

answered Jan 10 '17 at 21:58

Kristofersen

2,736
1
15
31

Delete identical objects

3 Answers3