bind_row datafrane within a list in r-CodePudding

I have a list of three dataframes as follow:

x1 <- data.frame(rnorm(5), rnorm(5))
x2 <- data.frame(rnorm(5), rnorm(5))
x3 <- data.frame(rnorm(5), rnorm(5))

list1 <- list(x1,x2,x3)
list1

I was trying to combine x1 to x2and x3 respectivelly using for loop with bind_row function like this:

df <- list()
for(i in 2: length(list1)){
  df[[i]] <- bind_rows(list1[1], list1[i])
}

The output that I got contains three elements with the first element as NULL value. I would like to remove this first element of the outcome list. How can I do that with my for loop here. I already did exlcude this by doing seperately but now I would like to do that with for loop.

CodePudding user response：

The reason why your first element is NULL is that df is an empty list to which you are assigning a 2nd and 3rd element but not a first element (since the for loop starts at 2). Simply assign the results to df[[i-1]] instead of df[[i]] so that the indexing starts at 1.

x1 <- data.frame(rnorm(5), rnorm(5))
x2 <- data.frame(rnorm(5), rnorm(5))
x3 <- data.frame(rnorm(5), rnorm(5))

list1 <- list(x1,x2,x3)

df <- list()
for(i in 2:length(list1)){
  df[[i - 1]] <- dplyr::bind_rows(list1[[1]], list1[[i]])
}

resulting in

df
#> [[1]]
#>      rnorm.5.  rnorm.5..1
#> 1   0.5357839 -0.01977554
#> 2   0.3767749  0.08128024
#> 3  -1.4592968  0.32772859
#> 4   1.1320294  0.11573657
#> 5  -1.6258767  0.89518999
#> 6   1.9629658 -0.31006782
#> 7   1.2439470  0.33417400
#> 8  -0.2733596  0.82149212
#> 9  -0.5620108  2.25258025
#> 10 -0.2034522 -1.20062231
#> 
#> [[2]]
#>       rnorm.5.  rnorm.5..1
#> 1   0.53578394 -0.01977554
#> 2   0.37677495  0.08128024
#> 3  -1.45929675  0.32772859
#> 4   1.13202945  0.11573657
#> 5  -1.62587667  0.89518999
#> 6   0.23592057  1.80902101
#> 7  -0.31696084  0.71427818
#> 8   0.23018058  0.92512042
#> 9   0.08847981 -0.26462483
#> 10 -0.24086157 -0.66625234

^{Created on 2022-07-28 by the reprex package (v2.0.1)}