How to reproduce the result of pivot_longer with reshape in base R?-CodePudding

Consider the cprefm object:

library(conjoint)

data(chocolate)

With pivot_longer:

library(dplyr)
library(tidyr)

cprefm %>% 
  pivot_longer(., 1:16, "profile", "rating") %>% 
  head(16)

# A tibble: 16 × 2
   profile   value
   <chr>     <int>
 1 profile1     14
 2 profile2     15
 3 profile3      5
 4 profile4      2
 5 profile5      1
 6 profile6     11
 7 profile7      3
 8 profile8     10
 9 profile9     16
10 profile10    13
11 profile11    12
12 profile12     7
13 profile13     6
14 profile14     9
15 profile15     4
16 profile16     8

I couldn't reproduce this with the reshape function:

cprefm |>
  (\(x) reshape(x, varying = 1:16, times = names(x)[1:16], timevar = "profile", 
                v.names = "values", direction = "long"))() |> 
  (\(x) head(x, 16))()

             profile values id
1.profile1  profile1     14  1
2.profile1  profile1     16  2
3.profile1  profile1      7  3
4.profile1  profile1      9  4
5.profile1  profile1      7  5
6.profile1  profile1     14  6
7.profile1  profile1      3  7
8.profile1  profile1      2  8
9.profile1  profile1      1  9
10.profile1 profile1      4 10
11.profile1 profile1      4 11
12.profile1 profile1     14 12
13.profile1 profile1      7 13
14.profile1 profile1     14 14
15.profile1 profile1     10 15
16.profile1 profile1      4 16

I have tried in many ways to modify varying argument, but I have not been able to reproduce the behavior of tidyr::pivot_longer. Note that even row.names has column names, but I wouldn't like that either.

I would like it to look identical to pivot_longer.

CodePudding user response：

If not using reshape is okay, this might works...

x <- as.data.frame(t(cprefm))

y <- data.frame(
  profile = rownames(x),
  value = unlist(x)
)
head(y,16)

     profile value
1   profile1    14
2   profile2    15
3   profile3     5
4   profile4     2
5   profile5     1
6   profile6    11
7   profile7     3
8   profile8    10
9   profile9    16
10 profile10    13
11 profile11    12
12 profile12     7
13 profile13     6
14 profile14     9
15 profile15     4
16 profile16     8

CodePudding user response：

The reshape command in the question is correct except for row names, row order and an extra id column so just fix those up.

out <- reshape(cprefm, dir = "long", varying = 1:16, 
  v.names = "value", timevar = "profile", times = names(cprefm))
out <- out[order(out$id), 1:2]
rownames(out) <- NULL

out.piv <- cprefm %>% pivot_longer(1:16, "profile", "rating")

identical(out, as.data.frame(out.piv))
## [1] TRUE

CodePudding user response：

For a complete pivot in base I'd use stack, no edited to fiddle it into an exact match with pivot_longer:

result = cprefm |> stack() |> setNames(c("value", "profile")) |> rev() 
result = result[order((1:nrow(result) - 1) %% nrow(cprefm), result$profile), ]
rownames(result) = 1:nrow(result)
result
#      profile value
# 1   profile1    14
# 2   profile2    15
# 3   profile3     5
# 4   profile4     2
# 5   profile5     1
# 6   profile6    11
# 7   profile7     3
# 8   profile8    10
# 9   profile9    16
# 10 profile10    13
# 11 profile11    12
# 12 profile12     7
# 13 profile13     6
# 14 profile14     9
# 15 profile15     4
# 16 profile16     8
# 17  profile1    16
# 18  profile2    15
# 19  profile3     7
# 20  profile4    14
# ...