Str2double gives NaN

Question

Praveen Kumar 2023-1-30

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1902885-str2double-gives-nan

编辑： Stephen23 2023-2-2

采纳的回答： Stephen23

X = ["3.716,3.711,3.719,3.714,3.714,3.711,3.722,3.712,3.715,3.715,3.717,3.721,3.713,3.714,0.000"];

Y = str2double(X);

I am trying to convert the above string to double. However, using above code, the Y value is 'NaN'.

'str2num(X)' gives appropriate/required results.

Y = [3.71600000000000 3.71100000000000 3.71900000000000 3.71400000000000 3.71400000000000 3.71100000000000 3.72200000000000 3.71200000000000 3.71500000000000 3.71500000000000 3.71700000000000 3.72100000000000 3.71300000000000 3.71400000000000 0]

However, 'str2num' is not supported in code generation. Is there any alternative?

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Answer 1

Stephen23 2023-1-30

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1902885-str2double-gives-nan#answer_1159275

在 MATLAB Online 中打开

https://www.mathworks.com/matlabcentral/answers/437449-matlab-coder-giving-issue-with-textscan#answer_354189

X = "3.716,3.711,3.719,3.714,3.714,3.711,3.722,3.712,3.715,3.715,3.717,3.721,3.713,3.714,0.000";
str = X{1}; % character vector
idx = str==',';
idy = diff([true,idx,true]);
idb = find(idy<0);
ide = find(idy>0)-1;
num = numel(idb);
tmp = cell(num,1);
for k = 1:num
    tmp{k} = str(idb(k):ide(k));
end
vec = str2double(tmp)
vec = 15×1
    3.7160
    3.7110
    3.7190
    3.7140
    3.7140
    3.7110
    3.7220
    3.7120
    3.7150
    3.7150

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Stephen23 2023-2-2

编辑：Stephen23 2023-2-2

在 MATLAB Online 中打开

matlab_error_test.csv

M = readmatrix('matlab_error_test.csv', 'Range',2, 'Delimiter',{',','"'}, 'ConsecutiveDelimitersRule','join')
M = 13×25
  512.0000         0    7.6800    0.0300         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0  -25.0000    3.0000   58.0000         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0  -34.0000    3.0000   58.0000         0         0         0
  512.0000         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0  -30.0000   18.0000         0         0         0         0
  512.0000         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0  -64.0000   20.0000         0         0         0         0
  512.0000         0         0         0         0         0         0         0         0         0         0    6.9120   30.9800   61.6990   53.2470   31.4850    7.0000         0  -15.0000    2.0000         0         0         0         0         0
         0    3.7710    3.7770    3.7780    3.7800    3.7800    3.7780    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0   31.0000   31.0000   32.0000   31.0000   32.0000   30.0000   30.0000   30.0000         0
         0    3.7710    3.7770    3.7790    3.7800    3.7790    3.7790    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0   31.0000   31.0000   32.0000   31.0000   32.0000   31.0000   30.0000   30.0000         0
         0    3.7710    3.7770    3.7780    3.7810    3.7790    3.7780    3.7500    3.7730    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0   31.0000   31.0000   32.0000   31.0000   32.0000   30.0000   30.0000   30.0000         0
         0    3.7710    3.7770    3.7780    3.7810    3.7790    3.7790    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0   31.0000   31.0000   32.0000   31.0000   32.0000   30.0000   30.0000   30.0000         0
X = M(:,2:16)
X = 13×15
         0    7.6800    0.0300         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0         0         0         0         0         0
         0         0         0         0         0         0         0         0         0         0    6.9120   30.9800   61.6990   53.2470   31.4850
    3.7710    3.7770    3.7780    3.7800    3.7800    3.7780    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0
    3.7710    3.7770    3.7790    3.7800    3.7790    3.7790    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0
    3.7710    3.7770    3.7780    3.7810    3.7790    3.7780    3.7500    3.7730    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0
    3.7710    3.7770    3.7780    3.7810    3.7790    3.7790    3.7500    3.7720    3.7790    3.7810    3.7750    3.7830    3.7810    3.7740         0

Praveen Kumar 2023-2-2

Thank you very much. Understood!

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Answer 2

Askic V 2023-1-30

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1902885-str2double-gives-nan#answer_1159205

在 MATLAB Online 中打开

Try this:

X = "3.716,3.711,3.719,3.714,3.714,3.711,3.722,3.712,3.715,3.715,3.717,3.721,3.713,3.714,0.000";
newStr = split(X,',')
Y = str2double(newStr)

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Praveen Kumar 2023-1-30

Thanks for the quick response. Even though the code works, 'split' is not supported in C/C++ code generation.

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Answer 3

Askic V 2023-1-30

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1902885-str2double-gives-nan#answer_1159285

编辑：Askic V 2023-1-30

在 MATLAB Online 中打开

I would also like to suggest this solution:

X = "3.716,3.711,3.719,3.714,3.714,3.711,3.722,3.712,3.715,3.715,3.717,3.721,3.713,3.714,0.200";
f = strfind(X, ","); % find indices of delimiter
Y = zeros(1, numel(f)+1); % initialize output array
X_char = convertStringsToChars(X);
j = 1;
for i = 1:numel(f) 
    start = j;
    Y(i) = str2double(X_char(j:f(i)-1));
    j = f(i)+1;
end
Y(end) = str2double(X_char(f(i)+1:end)); % add last element
Y
Y = 1×15
    3.7160    3.7110    3.7190    3.7140    3.7140    3.7110    3.7220    3.7120    3.7150    3.7150    3.7170    3.7210    3.7130    3.7140    0.2000