Arranging Columns in R

Question

I have data of the form:

              Department            LengthAfter
1                     A                  8.42
2                     B                 10.93
3                     D                  9.98
4                     A                 10.13
5                     B                 10.54
6                     C                  7.82
7                     A                  9.55
8                     D                 12.53
9                     C                  7.87

I would like to make a new table or dataframe in which the column header is each department (A, B, C, D) and the Lengths under each column are the values on LengthAfter corresponding to each department. e.g.

A       B         C         D
8.42   10.93     7.82      9.98

Can anyone help with this? Thank you

Welcome to SO; question has nothing to do with `statistics`, kindly do not spam irrelevant tags (removed). — desertnaut, Mar 29 '21 at 01:26
People are generally more likely to help if you include your data in a reproducible format (i.e., with `dput`). You have multiple readings for each of the departments - how should they be collapsed into a single reading? Is it an average? Or will the departments be repeated multiple times in the columns? — Conor Neilson, Mar 29 '21 at 08:04

score 1 · Answer 1 · answered Mar 28 '21 at 21:54

Using tidyverse, you can use pivot_wider to pivot your data into the desired form. Before that, you will need to sort (arrange) by Department first, if you want to include the values from LengthAfter in the order of appearance, and have the columns in order as above.

library(tidyverse)

df %>%
  arrange(Department) %>%
  group_by(Department) %>%
  mutate(rn = row_number()) %>%
  pivot_wider(names_from = "Department", values_from = "LengthAfter") %>%
  select(-rn)

Output

      A     B     C     D
  <dbl> <dbl> <dbl> <dbl>
1  8.42  10.9  7.82  9.98
2 10.1   10.5  7.87 12.5 
3  9.55  NA   NA    NA

score 0 · Answer 2 · answered Mar 29 '21 at 12:34

0

You can use package reshape2 for this

Library (reshape2)

Df_new <- dcast(df_old, Department~LengthAfter)

answered Mar 29 '21 at 12:34

Sg2403

1
2

jubilatious1 · Answer 3 · 2021-03-29T22:38:25.487

Base-R

dept_length <- read.csv("/Users/usr/SO_Department_LengthAfter.tsv", sep="\t");
dl_list <- with(dept_length, tapply(LengthAfter, Department, `c`));
n.obs <- sapply(dl_list, length);
seq.max <- seq_len(max(n.obs));
sapply(dl_list, `[`, i = seq.max);

Returns:

         A     B    C     D
[1,]  8.42 10.93 7.82  9.98
[2,] 10.13 10.54 7.87 12.53
[3,]  9.55    NA   NA    NA

References:

Arranging Columns in R

3 Answers3