Get error message of 'Error using max Invalid data type. First argument must be numeric or logical' when I attempt to apply max function to a column of data

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Angela Ebirim 2018-10-3

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此问题的直接链接

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评论： Angela Ebirim 2018-10-3

采纳的回答： Stephen23

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Hi,

I'm new to MATLAB and am trying to apply the max function to the following column of data:

1101 
5277 
5186 
0032 
8598 
3829 
4764 
5781 
4862 
0546 
7107 
164 
734 
4084 
6407 
3794 
3654 
1301 
4296 
0708 
1891 
27 
4901 
3261 
5649 
945 
828 
957 
176 
203 
2524 
5894 
2482 
8918 
2111 
9334 
0959 
6063 
836 
3534 
4069 
8825 
708 
7737 
8247 
0931 
0702 
8014 
       11.7 
5416 
5402 
3077 
4239 
6031 
3328 
3589 
2742 
6397 
3102 
4536 
8254 
1793 
279 
908 
959 
2182 
2951 
236 
4994 
341 
136 
3345 
0062 
2259 
0269 
5479 
5386 
0365 
274 
1077 
7292 
1884 
3557 
7687 
5159 
5172 
1802 
002 
5204 
0594 
7077 
6366 
8707 
3054 
2934 
394 
4369 
with the following response:

Error using max Invalid data type. First argument must be numeric or logical.

I can't see what I'm doing wrong.

Can someone please help ?

Thanks

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Stephen23 2018-10-3

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What is the class of that data? Tell us the output of this command:

whos NameOfThatVariable

Angela Ebirim 2018-10-3

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Name       Size            Bytes  Class    Attributes
x         97x1              1824  table

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Answer 1

Stephen23 2018-10-3

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编辑：Stephen23 2018-10-3

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Your data has class table. Tables are a container class: they contain data of other classes:

https://www.mathworks.com/help/matlab/tables.html

The max function, like most other numeric operations, only accepts data of numeric classes:

https://www.mathworks.com/help/matlab/numeric-types.html

You need to get the numeric data out of that table (container) before you can use it with a numeric operation. Getting numeric data out of a table is easy using any of the syntaxes that tables have for accessing their contents:

https://www.mathworks.com/help/matlab/matlab_prog/access-data-in-a-table.html

Probably you want something like

max(x.var)

where var is the name of the column (variable) in that table. You might find summary useful too.

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Angela Ebirim 2018-10-3

Thank you very much!

I did the following:-

extracting data from a table into an arrayx = c{:, end-1}
displaying the maximum value in the array and it's index[imax, indx] = max(x)imax = 22.2030 ; indx = 30

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