如果行包含 R 中同一变量的两个值，则转置数据帧

Question

I'm dealing with a dataframe that contains a variable named "Marker" which shows two values all the samples I collected. The dataframe is, for instance, as follows:

Sample.File Sample.Name Marker value
1            a         a_1    xxx    16
2            a         a_1    xxx    18
3            a         a_1    yyy    16
4            a         a_1    yyy    20
5            a         a_1    zzz     9
6            a         a_1    zzz    13
7            b         b_1    xxx    10
8            b         b_1    xxx    10
9            b         b_1    yyy     6
10           b         b_1    yyy    12
11           b         b_1    zzz    14
12           b         b_1    zzz    14

which is provided by the following code:

data <- data.frame(
   Sample.File = as.factor(c("a", "a", "a", "a", "a", "a", "b", "b", "b", "b",
                             "b", "b")),
   Sample.Name = as.factor(c("a_1", "a_1", "a_1", "a_1", "a_1", "a_1", "b_1",
                             "b_1", "b_1", "b_1", "b_1", "b_1")),
        Marker = as.factor(c("xxx", "xxx", "yyy", "yyy", "zzz", "zzz", "xxx",
                             "xxx", "yyy", "yyy", "zzz", "zzz")),
   value = c(16L, 18L, 16L, 20L, 9L, 13L, 10L, 10L, 6L, 12L, 14L, 14L)
)

---

The new dataframe I'd like to work with is should be achieved by transposing the current data, but maintaining the columns Sample.File and Sample.Name for all the collected samples. Furthermore, I'd like to obtain new variables to be labelled as follows (eg xxx & xxx.1, yyy & yyy.1, zzz & zzz.1) for the column labelled as "value".

The table I'd like to achieve looks like the following:

  Sample.File Sample.Name xxx xxx.1 yyy yyy.1 zzz zzz.1
1           a         a_1  16    18  16    20   9    13
2           b         b_1  10    10   6    12  14    14

---

I'd like to use a code without writing the name of the labels reported into "Marker" column (since I could obtain up to 100 different labels). I tried to use the following code but I couldn't achieve my goal:

I tried to use the following code but I couldn't achieve my goal:

library(dplyr)
library(tidyr)
data %>%
  gather(Sample.File, Sample.Name) %>%
  spread(value)

Error: `var` must evaluate to a single number or a column name, not a double vector
Run `rlang::last_error()` to see where the error occurred.
In addition: Warning message:
attributes are not identical across measure variables;
they will be dropped

I'd be very grateful if anybody could attend to this matter!

Answer 1

Here is one way to do it. We can create an ID for each Marker and then create a column. After that, we can convert it to wide format.

library(dplyr)
library(tidyr)

data2 <- data %>%
  group_by_at(vars(-value)) %>%
  mutate(N = row_number() - 1) %>%
  unite(col = "Marker", Marker, N, sep = ".") %>%
  pivot_wider(names_from = "Marker", values_from = "value") %>%
  ungroup()
data2
# # A tibble: 2 x 8
#   Sample.File Sample.Name xxx.0 xxx.1 yyy.0 yyy.1 zzz.0 zzz.1
#   <fct>       <fct>       <int> <int> <int> <int> <int> <int>
# 1 a           a_1            16    18    16    20     9    13
# 2 b           b_1            10    10     6    12    14    14