Question

I have a text file that looks like this. I would like to extract the total number of “A” and “E” characters.

>pr1
FSVSQNNPAE
>pr2
MAKERAHSQ
>pr3
RRRDKINNWIVQL

I would like to get the output like this

>pr1 
Total number of A - 1 
Total number of E - 1   

>pr2
Total number of A – 2
Total number of E - 1

>pr3
Total number of A – 0
Total number of E – 0

How can I do this with awk?

Answer 1

One way. When found a line beginning with >, read next one, save it in str variable and count number of substitution for each letter.

awk '
    $1 ~ /^>/ {
        getline str
        num_a = gsub( /A/, "", str )
        num_e = gsub( /E/, "", str )
        printf "%s\nTotal number of A - %d\nTotal number of E - %d\n\n", $0, num_a, num_e
    }
' infile

Output:

>pr1                                                                                                                                                                                                                                         
Total number of A - 1                                                                                                                                                                                                                        
Total number of E - 1                                                                                                                                                                                                                        

>pr2                                                                                                                                                                                                                                         
Total number of A - 2                                                                                                                                                                                                                        
Total number of E - 1                                                                                                                                                                                                                        

>pr3                                                                                                                                                                                                                                         
Total number of A - 0                                                                                                                                                                                                                        
Total number of E - 0