如何在 R 中获得 Ns 的 aa 频率

Question

Here is part of my data

df<-read.table (text="  Colour Time1    Time2   Time3   Time4   Time5   Time6
Yellow  N   Y   N   N   N   Y
Red Y   N   N   N   N   Y
Yellow  N   N   N   N   N   Y
Red N   N   N   Y   Y   Y
Yellow  N   N   N   N   N   Y
Red Y   N   N   N   N   Y
Yellow  N   Y   N   N   Y   Y

", header=TRUE)

I want to get the following outcome:

Time    Yellow  Red
Time1   4   1
Time2   2   3
Time3   4   3
Time4   4   2
Time5   3   2
Time6   0   0

As you can see, I want to count the number of Ns for each time. For example, Time 1 has only 4 Ns in Yellow and 1 N in Red. I think we need to use group_by and then mutate for frequencies of Ns, but I am not clear how to this.

Answer 1

An option is to reshape to 'long' format with pivot_longer on the 'Time' columns, then reshape it back to 'wide' with pivot_wider' while specifying the values_fn to get the sum` of logical expression ie count of 'N'

library(dplyr)
library(tidyr)
df %>% 
  pivot_longer(cols = starts_with('Time'), names_to = 'Time') %>% 
  pivot_wider(names_from = Colour, values_from = 'value',
     values_fn = function(x) sum(x == 'N'))

-output

# A tibble: 6 x 3
  Time  Yellow   Red
  <chr>  <int> <int>
1 Time1      4     1
2 Time2      2     3
3 Time3      4     3
4 Time4      4     2
5 Time5      3     2
6 Time6      0     0

---

Or do a group by summarise across the 'Time' columns and then transpose the output

library(data.table)
 df %>% 
     group_by(Colour) %>% 
     summarise(across(everything(), ~ sum(. =='N'))) %>%
     data.table::transpose(make.names = 'Colour', keep.names = 'Time')

-output

   Time Red Yellow
1 Time1   1      4
2 Time2   3      2
3 Time3   3      4
4 Time4   2      4
5 Time5   2      3
6 Time6   0      0