El lunes, 6 de octubre de 2014 03:01:07 UTC-5, JVaz escribió:
>
> Hello, I am new in Julia and it's the first time I publish here, but I
> actually would find it useful to modify a string. For example, I want to do:
>
>
string = "ACTGACTG"
> string[3] = A --> (error)
>
There is no particular reason to treat the sequence as a string; it's just
a collection of symbols.
So an option is to replace it with an array of characters:
julia> sequence = "ACTGACTG"
"ACTGACTG"
julia> bases = [c for c in sequence]
8-element Array{Any,1}:
'A'
'C'
'T'
'G'
'A'
'C'
'T'
'G'
julia>
julia> bases[3] = 'A'
'A'
julia> bases'
1x8 Array{Any,2}:
'A' 'C' 'A' 'G' 'A' 'C' 'T' 'G'
(I put ' after bases just to save space in the output; it takes the
transpose of the array.)
Note that since the entries of the array 'bases' are now characters, they
must be written with apostrophes / quotes instead of double quotes.
Also note that the code is more legible since there are readable and
understandable names for the variables.
The definition of bases uses an 'array comprehension'.
To get a bit more abstract, you could instead make an array of symbols:
julia> sequence = "ACTGACTG"
"ACTGACTG"
julia> bases = [symbol(c) for c in sequence];
julia>
julia> bases[3] = :A
:A
julia> bases'
1x8 Array{Any,2}:
:A :C :A :G :A :C :T :G
so that you really have abstract symbols, instead of characters.
(:A means "the symbol with the name 'A' in Julia; see, for example, my
tutorial)
The semicolon suppresses output.
>
> And I cannot use replace because I don't wanna change all the T, I just
> wanna change the third character in the string.
> For me, it is useful that they are trings because then "after a mutation"
> I can easily check if two strings are the same, e.g:
>
> How could I do that, then?
> Thanks
>
