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Keep first row by multiple columns in an R data.table
Display single row for each group in a data.tableremove duplicated.values in data.tableHow to remove duplicates based on 2 columns in `data.table`How can I remove duplicate rows?How to sort a dataframe by multiple column(s)Quickly reading very large tables as dataframesFiltering out duplicated/non-unique rows in data.tableRemove duplicated rowsWhat is the purpose of setting a key in data.table?data.table vs dplyr: can one do something well the other can't or does poorly?cbind specific columns from multiple data.tables efficientlyAdd columns to a data.table with joins efficientlyFinding duplicate columns in a data.table
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty height:90px;width:728px;box-sizing:border-box;
I'd like to get the first row only from a data.table, grouped by multiple columns.
This is straightforward with a single column, e.g.:
(dt <- data.table(x = c(1, 1, 1, 2),
y = c(1, 1, 2, 2),
z = c(1, 2, 1, 2)))
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(x)] # Remove rows 2-3
# x y z
# |1: 1 1 1
# |2: 2 2 2
But none of these approaches work when trying to remove based on two columns; i.e. in this case removing only row 2:
dt[!duplicated(x, y)] # Keeps only original data set
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(list(x, y))] # Same as above
dt[!duplicated(c("x", "y"))] # Same as above
dt[!duplicated(list("x", "y"))] # Same as above
dt[!duplicated(c(x, y))] # Only removes duplicates from first column
# x y z
# |1: 1 1 1
# |2: 2 2 2
Except for this, which only works in certain cases:
dt[!duplicated(paste0(x, y))]
# x y z
# |1: 1 1 1
# |2: 1 2 1
# |3: 2 2 2
r duplicates data.table
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
add a comment |
I'd like to get the first row only from a data.table, grouped by multiple columns.
This is straightforward with a single column, e.g.:
(dt <- data.table(x = c(1, 1, 1, 2),
y = c(1, 1, 2, 2),
z = c(1, 2, 1, 2)))
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(x)] # Remove rows 2-3
# x y z
# |1: 1 1 1
# |2: 2 2 2
But none of these approaches work when trying to remove based on two columns; i.e. in this case removing only row 2:
dt[!duplicated(x, y)] # Keeps only original data set
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(list(x, y))] # Same as above
dt[!duplicated(c("x", "y"))] # Same as above
dt[!duplicated(list("x", "y"))] # Same as above
dt[!duplicated(c(x, y))] # Only removes duplicates from first column
# x y z
# |1: 1 1 1
# |2: 2 2 2
Except for this, which only works in certain cases:
dt[!duplicated(paste0(x, y))]
# x y z
# |1: 1 1 1
# |2: 1 2 1
# |3: 2 2 2
r duplicates data.table
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
add a comment |
I'd like to get the first row only from a data.table, grouped by multiple columns.
This is straightforward with a single column, e.g.:
(dt <- data.table(x = c(1, 1, 1, 2),
y = c(1, 1, 2, 2),
z = c(1, 2, 1, 2)))
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(x)] # Remove rows 2-3
# x y z
# |1: 1 1 1
# |2: 2 2 2
But none of these approaches work when trying to remove based on two columns; i.e. in this case removing only row 2:
dt[!duplicated(x, y)] # Keeps only original data set
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(list(x, y))] # Same as above
dt[!duplicated(c("x", "y"))] # Same as above
dt[!duplicated(list("x", "y"))] # Same as above
dt[!duplicated(c(x, y))] # Only removes duplicates from first column
# x y z
# |1: 1 1 1
# |2: 2 2 2
Except for this, which only works in certain cases:
dt[!duplicated(paste0(x, y))]
# x y z
# |1: 1 1 1
# |2: 1 2 1
# |3: 2 2 2
r duplicates data.table
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
I'd like to get the first row only from a data.table, grouped by multiple columns.
This is straightforward with a single column, e.g.:
(dt <- data.table(x = c(1, 1, 1, 2),
y = c(1, 1, 2, 2),
z = c(1, 2, 1, 2)))
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(x)] # Remove rows 2-3
# x y z
# |1: 1 1 1
# |2: 2 2 2
But none of these approaches work when trying to remove based on two columns; i.e. in this case removing only row 2:
dt[!duplicated(x, y)] # Keeps only original data set
# x y z
# |1: 1 1 1
# |2: 1 1 2
# |3: 1 2 1
# |4: 2 2 2
dt[!duplicated(list(x, y))] # Same as above
dt[!duplicated(c("x", "y"))] # Same as above
dt[!duplicated(list("x", "y"))] # Same as above
dt[!duplicated(c(x, y))] # Only removes duplicates from first column
# x y z
# |1: 1 1 1
# |2: 2 2 2
Except for this, which only works in certain cases:
dt[!duplicated(paste0(x, y))]
# x y z
# |1: 1 1 1
# |2: 1 2 1
# |3: 2 2 2
r duplicates data.table
r duplicates data.table
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
asked Jul 23 '14 at 5:44
Max GhenisMax Ghenis
5,28763664
5,28763664
add a comment |
add a comment |
2 Answers
2
active
oldest
votes
data.table provides S3 methods for unique, duplicated and anyDuplicated
unique(dt, by = c('x','y'))
will give you what you want.
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
add a comment |
data.table does duplicated by key. From ?duplicated.data.table:
‘duplicated’ returns a logical vector indicating which rows of a
‘data.table’ have duplicate rows (by key).
setkey(dt, x, y)
dt[!duplicated(dt)]
## x y z
## 1: 1 1 1
## 2: 1 2 1
## 3: 2 2 2
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
bykeyby default, you can specify the by variables
– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
data.table provides S3 methods for unique, duplicated and anyDuplicated
unique(dt, by = c('x','y'))
will give you what you want.
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
add a comment |
data.table provides S3 methods for unique, duplicated and anyDuplicated
unique(dt, by = c('x','y'))
will give you what you want.
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
add a comment |
data.table provides S3 methods for unique, duplicated and anyDuplicated
unique(dt, by = c('x','y'))
will give you what you want.
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
data.table provides S3 methods for unique, duplicated and anyDuplicated
unique(dt, by = c('x','y'))
will give you what you want.
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
answered Jul 23 '14 at 5:53
mnelmnel
94k20222233
94k20222233
add a comment |
add a comment |
data.table does duplicated by key. From ?duplicated.data.table:
‘duplicated’ returns a logical vector indicating which rows of a
‘data.table’ have duplicate rows (by key).
setkey(dt, x, y)
dt[!duplicated(dt)]
## x y z
## 1: 1 1 1
## 2: 1 2 1
## 3: 2 2 2
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
bykeyby default, you can specify the by variables
– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
add a comment |
data.table does duplicated by key. From ?duplicated.data.table:
‘duplicated’ returns a logical vector indicating which rows of a
‘data.table’ have duplicate rows (by key).
setkey(dt, x, y)
dt[!duplicated(dt)]
## x y z
## 1: 1 1 1
## 2: 1 2 1
## 3: 2 2 2
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
bykeyby default, you can specify the by variables
– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
add a comment |
data.table does duplicated by key. From ?duplicated.data.table:
‘duplicated’ returns a logical vector indicating which rows of a
‘data.table’ have duplicate rows (by key).
setkey(dt, x, y)
dt[!duplicated(dt)]
## x y z
## 1: 1 1 1
## 2: 1 2 1
## 3: 2 2 2
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
data.table does duplicated by key. From ?duplicated.data.table:
‘duplicated’ returns a logical vector indicating which rows of a
‘data.table’ have duplicate rows (by key).
setkey(dt, x, y)
dt[!duplicated(dt)]
## x y z
## 1: 1 1 1
## 2: 1 2 1
## 3: 2 2 2
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
answered Jul 23 '14 at 5:55
Jake BurkheadJake Burkhead
5,73721631
5,73721631
bykeyby default, you can specify the by variables
– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
add a comment |
bykeyby default, you can specify the by variables
– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
by
key by default, you can specify the by variables– mnel
Jul 23 '14 at 5:56
by
key by default, you can specify the by variables– mnel
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
@mnel yea I upvoted your answer. Just thought this might shed some light on why the behaviour makes sense although it might seem strange
– Jake Burkhead
Jul 23 '14 at 5:56
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
dt[!duplicated(dt[,c("x","y"),with=F])] #seems to work
– akrun
Jul 23 '14 at 6:00
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
Thanks! Upvoted both but chose @mnel's for conciseness
– Max Ghenis
Jul 23 '14 at 6:03
add a comment |
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