## How to remove rows that contain identical pairs in opposite order in 2 columns

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In a correlation matrix I would like to get rid of the rows that are basically containing the same information as another row, except instead of "A" and "B" in var1 and var2 column contain "B" and "A" respectively

```   var1 var2      value
1   cyl  mpg -0.8521620
2  disp  mpg -0.8475514
3    wt  mpg -0.8676594
4   mpg  cyl -0.8521620
5  disp  cyl  0.9020329
6    hp  cyl  0.8324475
7    vs  cyl -0.8108118
8   mpg disp -0.8475514
9   cyl disp  0.9020329
10   wt disp  0.8879799
11  cyl   hp  0.8324475
12  mpg   wt -0.8676594
13 disp   wt  0.8879799
14  cyl   vs -0.8108118
```

Here we could drop for instance row 4 with mpg vs cyl since we have cyl vs mpg in row 1 already

I know I could filter for unique values in column value, BUT i don't want to do this as with my enormous data set there is actually a chance of getting identical correlation score with multiple pairs of columns. So it has to be done by name matching col `var1` and `var2`

I have this code so far to filter out data rows that are above a certain correlation value, but are not 1 (variable vs itself)

```mtcars %>%
as.matrix %>%
cor %>%
as.data.frame %>%
rownames_to_column(var = 'var1') %>%
gather(var2, value, -var1) %>%
filter(value > 0.8 | value < -0.8) %>%
filter(value != 1)
```

EDIT

```cor %>% {(function(x){x[upper.tri(x)]<-NA; x})(.)} %>%
```

is faster, but Rui's answer is more generic and can be applied to other situations other than cor matrix calculations.

```Unit: milliseconds
expr      min       lq     mean   median       uq      max neval cld
Andre 4.818793 5.113676 5.630160 5.408955 5.704825 22.33730   100  a
Rui   5.413692 5.761669 7.531146 6.003656 6.583750 78.02836   100   b
```

Help with removing duplicate reversed pairs in relational algebra , order of columns doesn't matter SELECT DISTINCT CASE WHEN If you want to delete those rows you might us the 2nd logic, the actual  Open Live Script The easiest way to remove a row or column from a matrix is to set that row or column equal to a pair of empty square brackets []. For example, create a 4-by-4 matrix and remove the second row. A = magic(4)

Another way is simply to `filter` by `var1 < var2`.

```mtcars %>%
as.matrix %>%
cor %>%
as.data.frame %>%
rownames_to_column(var = 'var1') %>%
gather(var2, value, -var1) %>%
filter(value > 0.8 | value < -0.8) %>%
filter(value != 1) %>%
filter(var1 < var2)
#  var1 var2      value
#1  cyl  mpg -0.8521620
#2 disp  mpg -0.8475514
#3  cyl disp  0.9020329
#4  cyl   hp  0.8324475
#5  mpg   wt -0.8676594
#6 disp   wt  0.8879799
#7  cyl   vs -0.8108118
```

Databases and SQL: Sorting and Removing Duplicates, How can I remove duplicate values from a query's results? quant measurement​, we can use the DISTINCT keyword on multiple columns. We can sort in the opposite order using DESC (for “descending”): Remember to use ORDER BY if you want the rows returned to have any sort of consistent or predictable order. Hold Ctrl key to select the two data columns separately, and then click Kutools > Select > Select Same & Different Cells, see screenshot: 2.

Using base:

```x <- cor(mtcars)
x[ upper.tri(x, diag = TRUE) | abs(x) < 0.8  ] <- NA
na.omit(data.frame(as.table(x)))
#    Var1 Var2       Freq
# 2   cyl  mpg -0.8521620
# 3  disp  mpg -0.8475514
# 6    wt  mpg -0.8676594
# 14 disp  cyl  0.9020329
# 15   hp  cyl  0.8324475
# 19   vs  cyl -0.8108118
# 28   wt disp  0.8879799
```

```microbenchmark::microbenchmark(
base = {
x <- cor(mtcars)
x[ upper.tri(x, diag = TRUE) | abs(x) < 0.8  ] <- NA
na.omit(data.frame(as.table(x)))
},
tidy = {
mtcars %>%
as.matrix %>%
cor %>% {(function(x){x[upper.tri(x, diag = T)]<-NA; x})(.)} %>%
as.data.frame %>%
rownames_to_column(var = 'var1') %>%
gather(var2, value, -var1) %>%
filter(value > 0.8 | value < -0.8)
})
# Unit: microseconds
# expr      min        lq      mean   median        uq      max neval
# base  683.994  718.1025  790.9333  750.099  796.2825  2288.63   100
# tidy 3278.397 3405.3260 3660.0932 3488.334 3676.3870 10212.20   100
```

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Filter for unique values or remove duplicate values, Keep in touch and stay productive with Teams and Microsoft 365, even when you'​re working remotely. Learn more. Row & columns. Filter for unique values or  The following is my sample dataset. First column contains the Date and other columns are firms. I have just included only four firms here; I have many more firms in my original dataset. If you see, observations are zeros for almost all firms in specific dates (for example, 01/01/2004, 19/01/2004 etc.). I need to remove those rows from my dataset.

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Table functions, The tables must all have the same row type structure. ReverseRows, Returns a table with the rows in reverse order. can be provided to handle multiple occurrence of the same key value in the attribute column. Unpivot, Given a list of table columns, transforms those columns into attribute-value pairs. If 2 columns are located on one worksheet, next to each other (adjacent) or not touching each other (nonadjacent), the removing duplicates is a bit more complex. We cannot delete entire rows that contain duplicate values because this would delete corresponding cells in the 2nd column too.