rewriting a table/data frame in r

Question

Here is an example of my data set:

Sensor ---- Time(GMT) ----- Temperature (°C)

1 ------- 24/06/2002 05:02:01 --- 33.855

2 ------- 24/06/2002 05:02:01 --- 33.827

3 ------- 24/06/2002 05:02:01 --- 33.104

4 ------- 24/06/2002 05:02:01 --- 33.787

1 ------- 24/06/2002 05:02:02 --- 33.609

2 ------- 24/06/2002 05:02:02 --- 33.609

3 ------- 24/06/2002 05:02:02 --- 33.610

4 ------- 24/06/2002 05:02:02 --- 33.608

To be able to work with it I have to rewrite this dataset, so that it looks like this:

Time ---------------------- Sensor1 - Sensor2 - Sensor3 -Sensor4

24/06/2002 05:02:01 -- 33.855 -- 33.827 -- 33.104 -- 33.787

24/06/2002 05:02:02 --33.609 -- 33.609 -- 33.610 -- 33.608

I'm a beginner in R, so this is pretty rough for me and I would be verv happy about suggestions or proposed solutions. Thanks.

Welcome to SO. It's easier to help you if you make your question reproducible including data and your code which can be used to test and verify possible solutions. Have a look at https://speakerdeck.com/jennybc/reprex-help-me-help-you?slide=5 & https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example? — Peter, Jun 04 '20 at 17:11

dario · Answer 1 · 2020-06-04T16:08:34.837

1.Creating an example data set:

df <- structure(list(Sensor = c(1L, 2L, 3L, 4L, 1L, 2L, 3L, 4L),
                     Time = c("24/06/2002 05:02:01", "24/06/2002 05:02:01", "24/06/2002 05:02:01", "24/06/2002 05:02:01",
                              "24/06/2002 05:02:02", "24/06/2002 05:02:02", "24/06/2002 05:02:02","24/06/2002 05:02:02"),
                     Temp = c(33.855, 33.827, 33.104, 33.787, 33.609, 33.609, 33.61, 33.608)),
                row.names = c(NA, -8L),
                class = c("data.table", "data.frame"))

2.Suggested solution using tidyr pivot_wider, a function that does exactly what you want ;)

library(dplyr)
library(tidyr)

df %>% 
  pivot_wider(names_from = Sensor, values_from = Temp, names_prefix="Sensor")

This Returns:

# A tibble: 2 x 5
  Time                Sensor1 Sensor2 Sensor3 Sensor4
  <chr>                 <dbl>   <dbl>   <dbl>   <dbl>
1 24/06/2002 05:02:01    33.9    33.8    33.1    33.8
2 24/06/2002 05:02:02    33.6    33.6    33.6    33.6

P.S. Actually there is no reason to use dplyr syntax, so here is the solution using only tidyr::pivot_wider:

pivot_wider(df, names_from = Sensor, values_from = Temp, names_prefix="Sensor")

Edit

Removed accidental dependency on data.table

@r2evans Thanks, I seem to have forgotten that fread is not a base function ;) — dario, Jun 04 '20 at 16:09

rewriting a table/data frame in r

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