Auto increment in R

Asked

Viewed 110 times

2

How do I generate an auto incremental ID field (1,2,3...) in a data.frame in R that in a new column?

meuDataFrase<- as_tibble(unique(tabelImportada$ColunaX))

I need to create a new column on that date.frame that has the line numbers because I will record this information in a dimensional table in postgres.

r

2 answers

4


One way to do this is to use the function rownames_to_column() package .

The example below includes ids for table rows iris. In this case it creates a column called "rowname".

library(tidyverse)
# só para imprimir melhor
tbl_iris <- as_tibble(iris)

tbl_iris %>% 
     rownames_to_column()
# A tibble: 150 x 6
   rowname Sepal.Length Sepal.Width Petal.Length Petal.Width Species
   <chr>          <dbl>       <dbl>        <dbl>       <dbl> <fct>  
 1 1                5.1         3.5          1.4         0.2 setosa 
 2 2                4.9         3            1.4         0.2 setosa 
 3 3                4.7         3.2          1.3         0.2 setosa 
 4 4                4.6         3.1          1.5         0.2 setosa 
 5 5                5           3.6          1.4         0.2 setosa 
 6 6                5.4         3.9          1.7         0.4 setosa 
 7 7                4.6         3.4          1.4         0.3 setosa 
 8 8                5           3.4          1.5         0.2 setosa 
 9 9                4.4         2.9          1.4         0.2 setosa 
10 10               4.9         3.1          1.5         0.1 setosa 
# … with 140 more rows

Another alterative is to create a column with the name you want using mutate() of combined with seq_len().

tbl_iris %>% 
  mutate(id = seq_len(nrow(.)))
# A tibble: 150 x 6
   Sepal.Length Sepal.Width Petal.Length Petal.Width Species    id
          <dbl>       <dbl>        <dbl>       <dbl> <fct>   <int>
 1          5.1         3.5          1.4         0.2 setosa      1
 2          4.9         3            1.4         0.2 setosa      2
 3          4.7         3.2          1.3         0.2 setosa      3
 4          4.6         3.1          1.5         0.2 setosa      4
 5          5           3.6          1.4         0.2 setosa      5
 6          5.4         3.9          1.7         0.4 setosa      6
 7          4.6         3.4          1.4         0.3 setosa      7
 8          5           3.4          1.5         0.2 setosa      8
 9          4.4         2.9          1.4         0.2 setosa      9
10          4.9         3.1          1.5         0.1 setosa     10
# … with 140 more rows

  • You’d better use the row_number function()

2

Always remember to bring a reproducible example. I created a DF simple as an example, but the concept is the same for others DF's.

Code:

x <- data.frame(z = c(51:101), y = c(50:100))

for(i in 1:nrow(x)) {
    
    x[i,3] <- i
    
}

Your case rownames are not numbers, use the following command before:

rownames(x) <- NULL

Note: I placed the column 3 in the for(), but you must put the number of the column you want the number of the row to appear.

Browser other questions tagged r

You are not signed in. Login or sign up in order to post.