Reshape: “Error: index out of bounds”

Question

I have a quite big dataframe with the following structure:

 image       coef    v3    v4    v5    v6   ... v20
    1         A       0     1     2     3        
    1         B       2     4     6     5
    1         C       1     2     4     7
    1         D       4     5     6     4
    2         A       2     3     4     5 
    2         B       2     3     4     5 
    2         C       2     3     4     5 
    2         D       2     3     4     5

And I need to end up with "flattened" structure on the coef variable for each image index. Now each image have the variables with the shape [4:20] but i need it to be [1:80] with the patern [A,B,C,D,A',B',C',D'...]. like this:

 image    v3    v4    v5    v6    v7    v8    v9    v10  ...   v80 
    1      0     2     1     4     1     4     2     5
    2      2     2     2     2     3     3     3     3

I tried to do:

reshape(df, timevar = "coef", idvar = "image", direction = "wide")

But i gives me the Error :

Error in data[, timevar] : subindex out of bounds

Also I tried the library Reshape2 with:

dcast(df, image~coef, value.var= )

but since I have more than one value.var column I cannot figure out how to do it.

I just want to point out that your data.frame is very tidy as it is, ideal for investigating with dplyr or plotting with ggplot2 for example. Make sure you have a valid reason for changing the convenient format :) — asachet, Apr 08 '16 at 10:56
@antoine-sac Yes i'm sure! I want it that way because I'm doing machine learning with the data and I need a single vector for each class :~~) Thanks for the advise! — Biel Stela, Apr 08 '16 at 11:13
Possible duplicate of [Reshaping time series data from wide to tall format (for plotting)](http://stackoverflow.com/questions/1181060/reshaping-time-series-data-from-wide-to-tall-format-for-plotting) — zx8754, Apr 08 '16 at 11:55

score 1 · Accepted Answer · answered Apr 08 '16 at 11:18

We can melt and then do the dcast

library(data.table)
dM <- melt(setDT(df1), id.var=c("image", "coef"))
dcast(dM, image~variable+coef, value.var="value")

Or use recast (which is a wrapper for melt/dcast) from reshape2

library(reshape2)
recast(df1, id.var=c("image", "coef"),image~variable+coef, value.var="value")
#  image v3_A v3_B v3_C v3_D v4_A v4_B v4_C v4_D v5_A v5_B v5_C v5_D v6_A v6_B v6_C v6_D
#1     1    0    2    1    4    1    4    2    5    2    6    4    6    3    5    7    4
#2     2    2    2    2    2    3    3    3    3    4    4    4    4    5    5    5    5

data

df1 <- structure(list(image = c(1L, 1L, 1L, 1L, 2L, 2L, 2L, 2L), 
coef = c("A", 
"B", "C", "D", "A", "B", "C", "D"), v3 = c(0L, 2L, 1L, 4L, 2L, 
2L, 2L, 2L), v4 = c(1L, 4L, 2L, 5L, 3L, 3L, 3L, 3L), v5 = c(2L, 
6L, 4L, 6L, 4L, 4L, 4L, 4L), v6 = c(3L, 5L, 7L, 4L, 5L, 5L, 5L, 
5L)), .Names = c("image", "coef", "v3", "v4", "v5", "v6"), 
class = "data.frame", row.names = c(NA, -8L))

Nice and neat! Thank you very much – Biel Stela Apr 08 '16 at 11:30 — Biel Stela, Apr 08 '16 at 11:30

Reshape: “Error: index out of bounds”

1 Answers1

data