Parse an array of strings - julia

Question

I have a 1D array of strings ( Array{String,1} ) which describe a matrix of Floats (see below). I need to parse this matrix. Any slick suggestions?
Julia 1.5
MacOS
Yes, I did read this in from a file. I don't want to read the whole thing in using CSV, because I want to maintain the option to read the entire file using memory I/O, which I don't think CSV has. Plus, I have some complex lines including strings and numbers, and strings and strings that I need to parse, which kind of rules out DelimitedFiles. The columns are separated by two spaces.
julia> lines[24+member_total:idx-1]
49-element Array{String,1}:
"0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01"
"0.0000000E+00 0.0000000E+00 1.9987500E-01 1.3308000E+01"
"0.0000000E+00 0.0000000E+00 1.1998650E+00 1.3308000E+01"
"0.0000000E+00 0.0000000E+00 2.1998550E+00 1.3308000E+01"
"0.0000000E+00 0.0000000E+00 3.1998450E+00 1.3308000E+01"
"0.0000000E+00 0.0000000E+00 4.1998350E+00 1.3308000E+01"
⋮
"0.0000000E+00 0.0000000E+00 5.9699895E+01 1.4000000E-01"
"0.0000000E+00 0.0000000E+00 6.0199890E+01 1.0100000E-01"
"0.0000000E+00 0.0000000E+00 6.0699885E+01 6.2000000E-02"
"0.0000000E+00 0.0000000E+00 6.1199880E+01 2.3000000E-02"
"0.0000000E+00 0.0000000E+00 6.1500000E+01 0.0000000E+00"

Answer 1

I am strongly against reinventing the wheel and using custom-made parsers due to practivcal robustness of such solutions in production.
If your file is in a single String use:
using DelimitedFiles
readdlm(IOBuffer(strs))
If your file as a Vector of Strings use
cat(readdlm.(IOBuffer.(strsa))...,dims=1)
Finally, there is not conflict in using memory maps togehther with CSV:
using Mmap
s = open("d.txt") # d.txt contains your lines
# if you want to read & wrtie use "w+" option
m = Mmap.mmap(s, Vector{UInt8}) # memory mapping of your file
readdlm(IOBuffer(m))
At the same time you can always set the stream to the beginning and read the data regardless the memory map:
seek(s,0)
readdlm(s)
seek(s,0) # reset the stream

Answer 2

strs = ["0.0000000E+00 0.0000000E+00 0.0000000E+00 1.3308000E+01",
"0.0000000E+00 0.0000000E+00 1.9987500E-01 1.3308000E+01",
"0.0000000E+00 0.0000000E+00 1.1998650E+00 1.3308000E+01"]
mapreduce(vcat, strs) do s
(parse.(Float64, split(s, " ")))'
end
3×4 Array{Float64,2}:
0.0 0.0 0.0 13.308
0.0 0.0 0.199875 13.308
0.0 0.0 1.19986 13.308

Answer 3

I made a work around. Not the most slick thing, but it works...
function rmspaces(line)
line = replace(line, "\t" => " ")
# println("line: ", line)
while occursin(" ", line)
line = replace(line, " "=>" ")
# println("line: ", line)
end
return line
end
function readmatrix(lines, numcolumns::Int64; type=Float64)
#Remove the spaces to one
for i=1:length(lines)
lines[i] = rmspaces(lines[i])
end
matrix = zeros(length(lines), numcolumns)
for i=1:length(lines)
idx = 1 # set the initial stop at the beginning
spot = 1
for j=1:length(lines[i])
if lines[i][j]==' ' && j>1 #Stops at spaces
number = parse(type,lines[i][idx:j]) #from the last stop to this one
idx = j #Set this stop in memory
matrix[i,spot] = number
spot += 1
end
end
if spot<numcolumns+1 #If there isn't a space after the last number,
#we need to attach the last number in every row. If the last number
#was appended, then the spot will be increased to be more than the number
#of columns.
number = parse(type, lines[i][idx:end])
matrix[i,spot] = number
end
end
return matrix
end