How to (idiomatically) read indexed arrays from a delimited text file?

I have text files from an external source that are formatted like so:

       0       0    -0.105961      0.00000       1       0     -1.06965      0.00000       1       1   -0.0187213    -0.240237       2       0    -0.124695      0.00000       2       1    -0.178982    0.0633255       2       2     0.760988    -0.213796       3       0     -1.96695      0.00000       3       1    0.0721285    0.0491248       3       2    -0.560517     0.267733       3       3    -0.188732    -0.112053       4       0   -0.0205364      0.00000⋮⋮⋮⋮      40      30     0.226833    -0.733674      40      31    0.0444837    -0.249677      40      32    -0.171559    -0.970601      40      33    -0.141848    -0.137257      40      34    -0.247042    -0.902128      40      35    -0.495114     0.322912      40      36     0.132215    0.0543294      40      37     0.125682     0.817945      40      38     0.181098     0.223309      40      39     0.702915     0.103991      40      40      1.11882    -0.488252

where the first two columns are the indices of a 2d array (say i and j), and the 3rd and 4th columns are the values for two 2d arrays (say p[:,:] and q[:,:]). What would be the idiomatic way in Python/Julia to read this into two 2d arrays?

There are some assumptions we can make: the arrays are lower triangular (i.e., the values only exist (or are nonzero) for j <= i), and the indices are increasing, that is, the last line can be expected to have the largest i (and probably j).

The current implementation assumes that maximum i and j is 40, and proceeds like so: (Julia minimal working example):

using OffsetArraysusing DelimitedFiles: readdlmn = 40p = zeros(0:n, 0:n)q = zeros(0:n, 0:n)open(filename) do infile    for i = 0:n        for j = 0:i            line = readline(infile)            arr = readdlm(IOBuffer(line))            p[i,j] = arr[3]            q[i,j] = arr[4]        end    endend

Note that this example also assumes that the index j changes the fastest, which is usually true, but in doing that it effectively ignores the first two columns of the data.

However, I'm looking for a solution that makes fewer assumptions about the data file (maybe only the lower-triangular one and the index increasing one). What would be a "natural" way of doing this in Julia or Python?