looking for regular expression to parse sparse data

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Hi,
i have a sparse mass matrix exported from ansys, and the data looks as follows:
[ 1, 1]: 1.157e-07 [ 1, 4]: 2.332e-08 [ 1, 7]: 2.146e-08 [ 1, 10]: 5.835e-08 [ 1, 13]: 4.043e-08 [ 1, 16]: 1.011e-08 [ 1, 19]: 8.211e-09 [ 1, 22]: 2.590e-08 [ 1, 25]:-3.475e-08 [ 1, 28]:-2.854e-08 [ 1, 31]:-2.987e-08 [ 1, 34]:-8.897e-08 [ 1, 37]:-1.351e-08 [ 1, 40]:-8.564e-09 [ 1, 43]:-9.072e-09 [ 1, 46]:-3.556e-08 [ 1, 49]:-6.093e-08 [ 1, 52]:-1.343e-08 [ 1, 55]:-8.914e-09 [ 1, 58]:-3.609e-08 [ 1, 61]:-3.609e-08 [ 1, 64]:-6.093e-08 [ 1, 67]:-1.343e-08 [ 1, 70]:-8.914e-09 [ 1, 118]: 5.625e-08 [ 1, 121]: 2.883e-08 [ 1, 130]: 2.507e-08 [ 1, 133]: 1.102e-08 [ 1, 142]:-3.891e-08 [ 1, 154]:-1.175e-08 [ 1, 166]:-3.459e-08 [ 1, 169]:-1.171e-08 [ 1, 181]:-1.171e-08 [ 1, 184]:-3.459e-08 [ 1, 187]:-8.513e-08 [ 1, 190]:-3.947e-08 [ 1, 193]:-3.466e-08 [ 1, 196]:-1.196e-08 [ 1, 958]: 1.944e-08 [ 1, 964]: 7.516e-09 [ 1, 970]:-2.705e-08 [ 1, 979]:-8.340e-09 [ 1, 988]:-7.965e-09 [ 1, 994]:-7.965e-09 [ 1, 1021]: 2.166e-08 [ 1, 1024]: 9.467e-09 [ 1, 1027]:-2.557e-08 [ 1, 1030]:-3.156e-08 [ 1, 1033]:-7.830e-09 [ 1, 1036]:-1.295e-08 [ 1, 1039]:-1.246e-08 [ 1, 1042]:-1.246e-08
Im looking to put this into a dense matrix, but well enough will be to store all the items in a cell array of 3 columns: x, y, data by N rows, where the regular expression will read to the end of the file.
I would then search the cell array for the largest index (X,Y) and initialize an array of that size, then copy the data over from the cell array to the matrix.
Is this possible?

Accepted Answer

Star Strider
Star Strider on 13 Nov 2020
This uses one regexp call to parse the data into specific cells that are read with sscanf, and then partitioned into individual columns using the reshape function in the ‘Out’ assignment. It may not be exactly what you intended (I doubt that is possible), however it has the virtue of produciing the desired result:
M = '[ 1, 1]: 1.157e-07 [ 1, 4]: 2.332e-08 [ 1, 7]: 2.146e-08 [ 1, 10]: 5.835e-08 [ 1, 13]: 4.043e-08 [ 1, 16]: 1.011e-08 [ 1, 19]: 8.211e-09 [ 1, 22]: 2.590e-08 [ 1, 25]:-3.475e-08 [ 1, 28]:-2.854e-08 [ 1, 31]:-2.987e-08 [ 1, 34]:-8.897e-08 [ 1, 37]:-1.351e-08 [ 1, 40]:-8.564e-09 [ 1, 43]:-9.072e-09 [ 1, 46]:-3.556e-08 [ 1, 49]:-6.093e-08 [ 1, 52]:-1.343e-08 [ 1, 55]:-8.914e-09 [ 1, 58]:-3.609e-08 [ 1, 61]:-3.609e-08 [ 1, 64]:-6.093e-08 [ 1, 67]:-1.343e-08 [ 1, 70]:-8.914e-09 [ 1, 118]: 5.625e-08 [ 1, 121]: 2.883e-08 [ 1, 130]: 2.507e-08 [ 1, 133]: 1.102e-08 [ 1, 142]:-3.891e-08 [ 1, 154]:-1.175e-08 [ 1, 166]:-3.459e-08 [ 1, 169]:-1.171e-08 [ 1, 181]:-1.171e-08 [ 1, 184]:-3.459e-08 [ 1, 187]:-8.513e-08 [ 1, 190]:-3.947e-08 [ 1, 193]:-3.466e-08 [ 1, 196]:-1.196e-08 [ 1, 958]: 1.944e-08 [ 1, 964]: 7.516e-09 [ 1, 970]:-2.705e-08 [ 1, 979]:-8.340e-09 [ 1, 988]:-7.965e-09 [ 1, 994]:-7.965e-09 [ 1, 1021]: 2.166e-08 [ 1, 1024]: 9.467e-09 [ 1, 1027]:-2.557e-08 [ 1, 1030]:-3.156e-08 [ 1, 1033]:-7.830e-09 [ 1, 1036]:-1.295e-08 [ 1, 1039]:-1.246e-08 [ 1, 1042]:-1.246e-08';
V = regexp(M, '\[', 'split');
R = sscanf([V{:}], '%d,%d]: %f');
Out = reshape(R, 3, []);
with:
FirstFiveColumns = Out(:,1:5)
producing:
FirstFiveColumns =
1 1 1 1 1
1 4 7 10 13
1.157e-07 2.332e-08 2.146e-08 5.835e-08 4.043e-08
with ‘x’ being the first row, ‘y’ being the second row, and the floating-point variables (I have no idea what they represent) the third row.
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