Pivot/Reshape data in R [duplicate] - r

Question

This question already has answers here:
Reshape horizontal to to long format using pivot_longer
(3 answers)
Closed 2 years ago.
Thank you all for your answers, I thought I was smarter than I am and hoped I would've understood any of it. I think I messed up my visualisation of my data aswell. I have edited my post to better show my sample data. Sorry for the inconvenience, and I truly hope that someone can help me.
I have a question about reshaping my data. The data collected looks as such:
data <- read.table(header=T, text='
pid measurement1 Tdays1 measurement2 Tdays2 measurement3 Tdays3 measurment4 Tdays4
1 1356 1435 1483 1405 1563 1374 NA NA
2 943 1848 1173 1818 1300 1785 NA NA
3 1590 185 NA NA NA NA 1585 294
4 130 72 443 70 NA NA 136 79
4 140 82 NA NA NA NA 756 89
4 220 126 266 124 NA NA 703 128
4 166 159 213 156 476 145 776 166
4 380 189 583 173 NA NA 586 203
4 353 231 510 222 656 217 526 240
4 180 268 NA NA NA NA NA NA
4 NA NA NA NA NA NA 580 278
4 571 334 596 303 816 289 483 371
')
Now i would like it to look something like this:
PID Time Value
1 1435 1356
1 1405 1483
1 1374 1563
2 1848 943
2 1818 1173
2 1785 1300
3 185 1590
... ... ...
How would i tend to get there? I have looked up some things about wide to longformat, but it doesn't seem to do the trick. Am reletively new to Rstudio and Stackoverflow (if you couldn't tell that already).
Kind regards, and thank you in advance.

Answer 1

Here is a slightly different pivot_longer() version.
library(tidyr)
library(dplyr)
dw %>%
pivot_longer(cols = -PID, names_to =".value", names_pattern = "(.+)[0-9]")
# A tibble: 9 x 3
PID T measurement
<dbl> <dbl> <dbl>
1 1 1 100
2 1 4 200
3 1 7 50
4 2 2 150
5 2 5 300
6 2 8 60
7 3 3 120
8 3 6 210
9 3 9 70
The names_to = ".value" argument creates new columns from column names based on the names_pattern argument. The names_pattern argument takes a special regex input. In this case, here is the breakdown:
(.+) # match everything - anything noted like this becomes the ".values"
[0-9] # numeric characters - tells the pattern that the numbers
# at the end are excluded from ".values". If you have multiple digit
# numbers, use [0-9*]

Answer 2

In the last edit you asked for a solution that is easy to understand. A very simple approach would be to stack the measurement columns on top of each other and the Tdays columns on top of each other. Although specialty packages make things very concise and elegant, for simplicity we can solve this without additional packages. Standard R has a convenient function aptly named stack, which works like this:
> exp <- data.frame(value1 = 1:5, value2 = 6:10)
> stack(exp)
values ind
1 1 value1
2 2 value1
3 3 value1
4 4 value1
5 5 value1
6 6 value2
7 7 value2
8 8 value2
9 9 value2
10 10 value2
We can stack measurements and Tdays seperately and then combine them via cbind:
data <- read.table(header=T, text='
pid measurement1 Tdays1 measurement2 Tdays2 measurement3 Tdays3 measurement4 Tdays4
1 1356 1435 1483 1405 1563 1374 NA NA
2 943 1848 1173 1818 1300 1785 NA NA
3 1590 185 NA NA NA NA 1585 294
4 130 72 443 70 NA NA 136 79
4 140 82 NA NA NA NA 756 89
4 220 126 266 124 NA NA 703 128
4 166 159 213 156 476 145 776 166
4 380 189 583 173 NA NA 586 203
4 353 231 510 222 656 217 526 240
4 180 268 NA NA NA NA NA NA
4 NA NA NA NA NA NA 580 278
4 571 334 596 303 816 289 483 371
')
cbind(stack(data, c(measurement1, measurement2, measurement3, measurement4)),
stack(data, c(Tdays1, Tdays2, Tdays3, Tdays4)))
Which keeps measurements and Tdays neatly together but leaves us without pid which we can add using rep to replicate the original pid 4 times:
result <- cbind(pid = rep(data$pid, 4),
stack(data, c(measurement1, measurement2, measurement3, measurement4)),
stack(data, c(Tdays1, Tdays2, Tdays3, Tdays4)))
The head of which looks like
> head(result)
pid values ind values ind
1 1 1356 measurement1 1435 Tdays1
2 2 943 measurement1 1848 Tdays1
3 3 1590 measurement1 185 Tdays1
4 4 130 measurement1 72 Tdays1
5 4 140 measurement1 82 Tdays1
6 4 220 measurement1 126 Tdays1
As I said above, this is not the order you expected and you can try to sort this data.frame, if that is of any concern:
result <- result[order(result$pid), c(1, 4, 2)]
names(result) <- c("pid", "Time", "Value")
leading to the final result
> head(result)
pid Time Value
1 1 1435 1356
13 1 1405 1483
25 1 1374 1563
37 1 NA NA
2 2 1848 943
14 2 1818 1173

Answer 3

tidyverse solution
library(tidyverse)
dw %>%
pivot_longer(-PID) %>%
mutate(name = gsub('^([A-Za-z]+)(\\d+)$', '\\1_\\2', name )) %>%
separate(name, into = c('A', 'B'), sep = '_', convert = T) %>%
pivot_wider(names_from = A, values_from = value)
Gives the following output
# A tibble: 9 x 4
PID B T measurement
<int> <int> <int> <int>
1 1 1 1 100
2 1 2 4 200
3 1 3 7 50
4 2 1 2 150
5 2 2 5 300
6 2 3 8 60
7 3 1 3 120
8 3 2 6 210
9 3 3 9 70

Answer 4

Considering a dataframe, df like the following:
PID T1 measurement1 T2 measurement2 T3 measurement3
1 1 100 4 200 7 50
2 2 150 5 300 8 60
3 3 120 6 210 9 70
You can use this solution to get your required dataframe:
iters = seq(from = 4, to = length(colnames(df))-1, by = 2)
finalDf = df[, c(1,2,3)]
for(j in iters){
tobind = df[, c(1,j,j+1)]
finalDf = rbind(finalDf, tobind)
}
finalDf = finalDf[order(finalDf[,1]),]
print(finalDf)
The output of the print statement is this:
PID T1 measurement1
1 1 1 100
4 1 4 200
7 1 7 50
2 2 2 150
5 2 5 300
8 2 8 60
3 3 3 120
6 3 6 210
9 3 9 70

Answer 5

Maybe you can try reshape like below
reshape(
setNames(data, gsub("(\\d+)$", "\\.\\1", names(data))),
direction = "long",
varying = 2:ncol(data)
)