遍历数据集的每一行和每一列

Question

I'm kind of new to R, and I need to convert several datasets into one big mysql table.

What I need is to iterate each row of the dataset and get each row adding the label of the column and value of the row as well as its id into a new row.

Example: Lets say the dataset below:

      ID    NAME    AGE
1     2589  Joe     31
2     2590  Joseph  15
3     2591  Maria   40

I need to turn it into:

      id   question  answer
1     2589 NAME      Joe
2     2589 AGE       31
3     2590 NAME      Joseph
4     2590 AGE       15
5     2591 NAME      Maria
6     2591 AGE       40

I need to do this to several datasets that doesn't have the same number of columns, but the result dataset should have the same format.

Can anyone help me?

Answer 1

Try tidyr::gather() . For your example assuming a data frame mydata :

library(tidyr)
mydata %>% 
  gather(question, answer, -ID)

Answer 2

Convert your table to long format using tidyr::gather then sort by ID

library(dplyr)
library(tidyr)

txt <- "ID    NAME    AGE
1     2589  Joe     31
2     2590  Joseph  15
3     2591  Maria   40"

df <- read.table(text = txt, header = TRUE)

df %>% 
  gather(key = "question", value = "answer", -ID) %>% 
  arrange(ID)

#>     ID question answer
#> 1 2589     NAME    Joe
#> 2 2589      AGE     31
#> 3 2590     NAME Joseph
#> 4 2590      AGE     15
#> 5 2591     NAME  Maria
#> 6 2591      AGE     40

Created on 2018-03-21 by the reprex package (v0.2.0).