converting string to num and table

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Sarvesh
Sarvesh 2024-8-22
编辑： Stephen23 2024-8-23
I have a table containing string data that represents cyclone certain and uncertain tracks. Each cell in the table may contain multiple track numbers (seperated by a space), where the presence of 'x' beside a number indicates uncertainty in that track. For example, in tempData(7,1) = "30 25x", '30' is a certain track, and '25' is uncertain.
I need to write a code that parses each cell in a column of tempData, separates the track numbers and their uncertainty markers ('x'), and outputs a (in this case) 4-column table for each column in tempData. The headers of the output table should be track1, uncert1, track2, uncert2, corresponding to the parsed tracks and their certainty indicators (marked by 0 or 1). If the input has 3 tracks, the then output table should have a 6 column table
Finally, I want to store each output table in a cell array marked by the varname of the input column (y98, y99, y20, etc), as I need to process over 200 columns in my original data.
I have attached a sample input (tempData) and output for the first coumn that i want (tempDataOut).
Thanks in advance.

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Stephen23
Stephen23 2024-8-22
编辑：Stephen23 2024-8-23
Ran in:
Tip for the future: upload your raw data, not a data extract that you have already imported and modified.
S = load('sample1.mat')
S = struct with fields:
tempData: [10x3 table] tempDataOut: [10x5 table]
S.tempData % lets take a look at the input data
ans = 10x3 table
y89 y90 y20 ________ ____________ __________________ "3x 4" {0x0 double} {[ 5]} "5" {'4x' } {'14 8 11 16x 18'} "11" {[ 23]} {0x0 cell } "15x" {'24x' } {[ 13]} "22x" {'33x' } {[ 17]} "26x" {0x0 cell } {0x0 cell } "30 25x" {'48x 46x' } {[ 28]} "" {[ 51]} {[ 35]} "32" {[ 52]} {0x0 cell } "35" {'53x' } {[ 42]}
That table data is a bit of a mess, so the first thing we will do is convert the table data to a consistent type (fixing the data file import would make this task easier/superfluous):
V = S.tempData.Properties.VariableNames;
T = varfun(@mystring,S.tempData)
T = 10x3 table
mystring_y89 mystring_y90 mystring_y20 ____________ ____________ ________________ "3x 4" "" "5" "5" "4x" "14 8 11 16x 18" "11" "23" "" "15x" "24x" "13" "22x" "33x" "17" "26x" "" "" "30 25x" "48x 46x" "28" "" "51" "35" "32" "52" "" "35" "53x" "42"
C = varfun(@myvarfun,T, 'OutputFormat','cell');
C = cellfun(@myrename,C,V, 'uni',0)
C = 1x3 cell array
{10x5 table} {10x5 table} {10x11 table}
S.tempDataOut % your expected output for comparison against C{1}
ans = 10x5 table
y89 track1 uncert1 track2 uncert2 ________ ______ _______ ______ _______ "3x 4" 3 1 4 0 "5" 5 0 0 0 "11" 11 0 0 0 "15x" 15 1 0 0 "22x" 22 1 0 0 "26x" 26 1 0 0 "30 25x" 30 0 25 1 "" 0 0 0 0 "32" 32 0 0 0 "35" 35 0 0 0
C{:} % all output tables
ans = 10x5 table
y89 track1 uncert1 track2 uncert2 ________ ______ _______ ______ _______ "3x 4" 3 1 4 0 "5" 5 0 0 0 "11" 11 0 0 0 "15x" 15 1 0 0 "22x" 22 1 0 0 "26x" 26 1 0 0 "30 25x" 30 0 25 1 "" 0 0 0 0 "32" 32 0 0 0 "35" 35 0 0 0
ans = 10x5 table
y90 track1 uncert1 track2 uncert2 _________ ______ _______ ______ _______ "" 0 0 0 0 "4x" 4 1 0 0 "23" 23 0 0 0 "24x" 24 1 0 0 "33x" 33 1 0 0 "" 0 0 0 0 "48x 46x" 48 1 46 1 "51" 51 0 0 0 "52" 52 0 0 0 "53x" 53 1 0 0
ans = 10x11 table
y20 track1 uncert1 track2 uncert2 track3 uncert3 track4 uncert4 track5 uncert5 ________________ ______ _______ ______ _______ ______ _______ ______ _______ ______ _______ "5" 5 0 0 0 0 0 0 0 0 0 "14 8 11 16x 18" 14 0 8 0 11 0 16 1 18 0 "" 0 0 0 0 0 0 0 0 0 0 "13" 13 0 0 0 0 0 0 0 0 0 "17" 17 0 0 0 0 0 0 0 0 0 "" 0 0 0 0 0 0 0 0 0 0 "28" 28 0 0 0 0 0 0 0 0 0 "35" 35 0 0 0 0 0 0 0 0 0 "" 0 0 0 0 0 0 0 0 0 0 "42" 42 0 0 0 0 0 0 0 0 0
function S = mystring(C)
% Convert cell array of mixed numeric/char/string to string array.
C(cellfun(@isempty,C)) = {''};
S = string(C);
end
function T = myvarfun(S)
% Convert string array to table (with certain & uncertain columns).
assert(~any(contains(S,'-')),'Minus character is not supported')
T = table(S);
C = regexprep(S,'(\d+)x','-$1');
N = numel(C);
M = nan(N,0);
for k = 1:N
V = sscanf(C{k},'%f');
M(k,1:numel(V)) = V;
end
U = +(M<0);
M = abs(M);
for k = 1:size(M,2)
T = addvars(T,M(:,k),U(:,k),'NewVariableNames',["track","uncert"]+k);
end
end
function T = myrename(T,v1)
% Rename first table column to v1.
T.Properties.VariableNames{1} = v1;
end
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Sarvesh
Sarvesh 2024-8-23
thanks @Stephen23. Just what i needed. Also, the original data was even more messier than the sample I gave which is why i did not put the whole original data. But i will keep your suggestion in mind for my future questions. Thanks once again.

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Karanjot
Karanjot 2024-8-22
Hi Sarvesh,
To achieve this task, you can write a script in MATLAB that processes each column of your tempData table, parses the track numbers and their uncertainty markers, and stores the results in a cell array. Here's a step-by-step guide to help you accomplish this:
  • Initialize Variables: Create a cell array to store the output tables, and define the headers for the output tables.
  • Parse Each Column: Loop through each column in tempData, and for each cell, split the string by spaces to separate track numbers and uncertainty markers.
  • To carry out the string manipulation as described above, You can use the strsplit function to split a string into parts based on a delimiter and the endsWith function to check if a string ends with a specified substring. For example:
parts = strsplit('30 25x', ' '); % Splits into {'30', '25x'}
isUncertain = endsWith('25x', 'x'); % Returns true
  • Create Output Table: For each parsed cell, determine the number of tracks and uncertainty indicators, and create a table with appropriate headers.
  • Store Results: Store each output table in the cell array with the corresponding variable name.
To know more about the functions mentioned above, Please refer to the following documentation:
https://www.mathworks.com/help/matlab/ref/strsplit.html
https://www.mathworks.com/help/matlab/ref/endswith.html
I hope this helps!

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