How to Melt single column in R

Question

How to melt single column from T1 to T2.

T1   
Mar-17  T2 
328  Mar-17 328
29.57  Mar-17 29.57
38.483  Mar-17 38.483
31.26  Mar-17 31.26
37.3  Mar-17 37.3
60.026  Mar-17 60.026
47.059  Mar-17 47.059
40.215  Mar-17 40.215
51.79  Mar-17 51.79
45.284  Mar-17 45.284
41.271  Mar-17 41.271
42.411  Mar-17 42.411

and what id I should use to get output in T4 from T3

T3    
Mar-17 Apr-17  T4 
328 396  Mar-17 328
29.57 216.57  Mar-17 29.57
38.483 116.483  Mar-17 38.483
31.26 168.26  Mar-17 31.26
37.3 128.3  Mar-17 37.3
60.026 82.026  Mar-17 60.026
47.059 113.059  Mar-17 47.059
40.215 165.215  Mar-17 40.215
51.79 80.79  Mar-17 51.79
45.284 185.284  Mar-17 45.284
41.271 183.271  Mar-17 41.271
42.411 204.411  Mar-17 42.411
   Apr-17 396
   Apr-17 216.57
   Apr-17 116.483
   Apr-17 168.26
   Apr-17 128.3
   Apr-17 82.026
   Apr-17 113.059
   Apr-17 165.215
   Apr-17 80.79
   Apr-17 185.284
   Apr-17 183.271
   Apr-17 204.411

When I am using stack

T2 <- stack(T1)

it is giving error message

Error in rep.int(names(x), lengths(x)) : invalid 'times' value

Is Mar-17 the column name or the first row? – neilfws Jun 07 '17 at 22:21 — neilfws, Jun 07 '17 at 22:21

score 2 · Accepted Answer · answered Jun 07 '17 at 22:50

I'm able to reproduce your error when I do not have column names (but rather have Mar-17 and Apr-17 as the first observation) so I am assuming that this is how your data is structured. If Mar-17 and Apr-17 are your column names, stack() should work.

In this case, you could set your variable names to be the values in the first row and then use stack() on everything excluding the first row:

names(T1) <- T1[1,]
T2 <- stack(T1[-1, , drop = F])

head(T2)
#       values    ind
#1     328 Mar-17
#2   29.57 Mar-17
#3  38.483 Mar-17
#4   31.26 Mar-17
#5    37.3 Mar-17
#6  60.026 Mar-17

names(T3) <- T3[1,]
T4 <- stack(T3[-1,])

head(T4)
#  values    ind
#1    328 Mar-17
#2  29.57 Mar-17
#3 38.483 Mar-17
#4  31.26 Mar-17
#5   37.3 Mar-17
#6 60.026 Mar-17

Data:

T1 <- structure(list(c("Mar-17", "328", "29.57", "38.483", "31.26", 
          "37.3", "60.026", "47.059", "40.215", "51.79", "45.284", "41.271", 
          "42.411")), class = "data.frame", row.names = c(NA, -13L))

T3 <- structure(list(c("Mar-17", "328", "29.57", "38.483", "31.26", 
          "37.3", "60.026", "47.059", "40.215", "51.79", "45.284", "41.271", 
          "42.411"), c("Apr-17", "396", "216.57", "116.483", "168.26", 
          "128.3", "82.026", "113.059", "165.215", "80.79", "185.284", 
          "183.271", "204.411")), row.names = c(NA, -13L), class = "data.frame")

Thanks Mike it worked well, you have been very generous to reproduce the data. — Anurag Sharma, Jun 08 '17 at 10:14

How to Melt single column in R

1 Answers1