Syntax error How to change data.table object columns value to maximum in R?

How to change data.table object columns value to maximum in R?

Sometimes we need to compare the maximum values or set some column of a data frame or data.table object to their maximums, especially in research studies that may require biasedness. Therefore, we can set all the column values to maximum. In case of a data.table object, we can use single square bracket to access and assign the column values to their maximum as shown in the below examples.

Example

Loading data.table package and creating a data.table object −

> library(data.table)
> x1<-rpois(20,5)
> x2<-rpois(20,5)
> DT1<-data.table(x1,x2)
> DT1

Output

x1 x2
1: 3 4
2: 3 5
3: 5 6
4: 10 5
5: 8 2
6: 3 4
7: 6 6
8: 2 8
9: 5 5
10: 1 3
11: 4 4
12: 4 3
13: 3 4
14: 9 5
15: 6 4
16: 4 10
17: 2 5
18: 6 2
19: 6 6
20: 3 7

Setting all values to maximum in both the columns of DT1 −

Example

> DT1[,":="(x1=max(x1),x2=max(x2))]
> DT1

Output

x1 x2
1: 10 10
2: 10 10
3: 10 10
4: 10 10
5: 10 10
6: 10 10
7: 10 10
8: 10 10
9: 10 10
10: 10 10
11: 10 10
12: 10 10
13: 10 10
14: 10 10
15: 10 10
16: 10 10
17: 10 10
18: 10 10
19: 10 10
20: 10 10

Example

> y1<-rnorm(20)
> y2<-rnorm(20)
> DT2<-data.table(y1,y2)
> DT2

Output

y1 y2
1: 0.023625687 1.4483042
2: 1.106287710 1.0704318
3: 1.467489995 -0.1895449
4: 0.547832725 -0.5910900
5: -0.733764184 0.1977163
6: 2.021397912 0.4160044
7: -0.001008175 -0.6264825
8: 0.237018174 -0.4992914
9: -0.842971527 -0.7227745
10: -1.444723647 -0.1965069
11: -2.415372720 0.2633523
12: 1.317615263 0.5652904
13: -0.858622646 1.1681279
14: -0.585999557 -0.5307442
15: 0.330628856 -0.7169733
16: 0.177377373 0.1853514
17: -0.061377177 -0.3185333
18: -0.180351581 -1.2435872
19: -1.040703567 1.6828731
20: 1.367891650 -0.3071294

Setting all values to maximum in both the columns of DT2 −

Example

> DT2[,":="(y1=max(y1),y2=max(y2))]
> DT2

Output

y1 y2
1: 2.021398 1.682873
2: 2.021398 1.682873
3: 2.021398 1.682873
4: 2.021398 1.682873
5: 2.021398 1.682873
6: 2.021398 1.682873
7: 2.021398 1.682873
8: 2.021398 1.682873
9: 2.021398 1.682873
10: 2.021398 1.682873
11: 2.021398 1.682873
12: 2.021398 1.682873
13: 2.021398 1.682873
14: 2.021398 1.682873
15: 2.021398 1.682873
16: 2.021398 1.682873
17: 2.021398 1.682873
18: 2.021398 1.682873
19: 2.021398 1.682873
20: 2.021398 1.682873
Updated on: 2021-01-04T06:44:17+05:30

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