How to exclude/extract empty rows/columns in a table?

Question

Ivan Mich 2023-2-8

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1908775-how-to-exclude-extract-empty-rows-columns-in-a-table

回答： Voss 2023-2-16

Hello,

I have a question about a code. I have a table with 8 columns (I use readtable command). In this file there are scattered blanks from column 5 to 8, and from column 1 to column 4.

I would like two files to be created from this file. one containing the filled (without blanks) columns 1 through 4, and the other file containing the filled without blanks columns 5 through 8.

I attach both the input (test_file.txt) and the two outputs (output1.txt & output2.txt) that I would like to have.

Could you please help me?

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Answer 1

KSSV 2023-2-8

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https://ww2.mathworks.cn/matlabcentral/answers/1908775-how-to-exclude-extract-empty-rows-columns-in-a-table#answer_1166510

编辑：KSSV 2023-2-8

在 MATLAB Online 中打开

T = readtable('https://in.mathworks.com/matlabcentral/answers/uploaded_files/1288860/test_file.txt');
% Remove empty rows 
idx  =  cellfun(@isempty,T.(1)) ;
T(idx,:) = [] ; 
% 
idx = isnan(T.(6)) ;
M = (1:height(T))' ;
idr = diff(find([1;diff(idx);1]));
D = mat2cell(M,idr(:),size(M,2)) ;
iwant = cell(length(D),1) ;
for i = 1:length(D)
    iwant{i} = T(D{i},:) ;
end

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Ivan Mich 2023-2-10

the problem is that your script separates only the code that have elements in columns 1-4 (and nan elements in the other columns of each row) into multiple files. the problem is that I would like to have a separated file for rows like row 11 of my input file (test_file.txt attached), that have nan elements in columns 1-4 and in columns 5-8 have numbers/elements..

Finally the purpose is to have two output files (output1.txt & output2.txt attached in this commend). I do not want to include rows like n.6 and n.7 in my input file that have completed all the columns with numbers/elements.

Could you please help me?

Ivan Mich 2023-2-11

Could you please help me?

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Answer 2

Voss 2023-2-16

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1908775-how-to-exclude-extract-empty-rows-columns-in-a-table#answer_1173430

在 MATLAB Online 中打开

test_file.txt

% read input file into table T
T = readtable('test_file.txt');
% get a logical matrix saying whether each element of the table is missing
% (NaN for numerics, '' for cell arrays of chars)
ism = ismissing(T);
% only output rows that have some missing value
rows_to_use = any(ism,2);
% rows without any missing value in the first 4 columns will go to output1
rows_for_output1 = ~any(ism(:,1:4),2);
% create two new tables from the original
output1 = T(rows_to_use & rows_for_output1,:);
output2 = T(rows_to_use & ~rows_for_output1,:);
% write the tables to their respective output files
writetable(output1,'output1.txt','Delimiter','\t','WriteVariableNames',false)
writetable(output2,'output2.txt','Delimiter','\t','WriteVariableNames',false)
% check the output files
type output1.txt
SAINT	38.6	22.3	10		NaN	NaN	NaN
MILAN	34	24	30		NaN	NaN	NaN
MILAN	39.3	26.8	30		NaN	NaN	NaN
MILAN	37.5	21	69		NaN	NaN	NaN
PARIS	40.5	25	5		NaN	NaN	NaN
FLORIDA	37.5	21	31		NaN	NaN	NaN
FLORIDA	37.5	24	602		NaN	NaN	NaN
FLORIDA	39.5	21	549		NaN	NaN	NaN
NAPOLI	37.5	21	205		NaN	NaN	NaN
type output2.txt
	NaN	NaN	NaN	CHINA	40.5	25	3.5