How to modify number of characters for numeric values in a cell array?

Question

Calabrese 2017-7-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/348881-how-to-modify-number-of-characters-for-numeric-values-in-a-cell-array

编辑： Calabrese 2017-7-15

Within a cell array, I would like to limit the number of characters allowed in each cell to 6. If the cell has more than 6 characters, I would like to remove the characters off of the end. i.e.

n_raw = 
    [  0.023391]
    [   0.31236]
    [ 0.0073958]
    [    0.6252]
    [    14.158]
    [    14.159]
    [  0.046701]
    [  0.095463]

to

n_raw = 
    [  0.0233]
    [  0.3123]
    [  0.0073]
    [  0.6252]
    [  14.158]
    [  14.159]
    [  0.0467]
    [  0.0954]

5 个评论
显示 3更早的评论隐藏 3更早的评论

Calabrese 2017-7-15

Could I convert them to characters, reduce them, and then convert them back to numbers?

per isakson 2017-7-15

在 MATLAB Online 中打开

Why not try?

You have to distinguish between internal representation and what's displayed.

>> cac{1} = 1/3;
cac{2} = 33.3;
cac
cac = 
    [0.3333]    [33.3000]
>> format long
>> cac
cac = 
    [0.333333333333333]    [33.299999999999997]

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Walter Roberson 2017-7-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/348881-how-to-modify-number-of-characters-for-numeric-values-in-a-cell-array#answer_274282

在 MATLAB Online 中打开

Under the assumption that each entry in the cell is a column vector, and cell itself is a column vector, but not assuming that each entry is a scalar:

 n_raw = {
     0.023391
     0.31236
     0.0073958
     0.6252
     14.158
     -14.159
     0.046701
     0.095463 };
rv = vertcat(n_raw{:});
new_n_raw = mat2cell( floor(abs(rv) * 10000) / 10000 .* sign(rv), cellfun(@length, n_raw), 1);

Note, however, that the only fractions that can be represented exactly in 4 decimal digits are the integer multiples of 1/16 (e.g., 5/16 or 6/16 = 3/8 can be represented exactly in 4 decimal digits, but 11/32 cannot be represented exactly in 4 decimal digits.) In all other cases, the rounding to 4 decimal digits will only look to work. For example, what looks like 0.023391 rounded to what looks like 0.0233 would actually become 0.02330000000000000126565424807267845608294010162353515625