Error with the division
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Hello everyone,
load('DATI_MAR_ANNUALI');
load('DATA_ECM');
a=DATIMARannuali;
b=DATIECMWFannuali;
c=(a-b)./a
d=c*100
this is my code, but I get an error trying to do the division; how can I solve it?
Thank you!
5 个评论
Steven Lord
2021-11-25
What is the full and exact text (everything displayed in red and/or orange in the Command Window) of the error and/or warning messages you receive when you run your code? The exact text of the messages may include information that will help us determine the problem or at least the next step to take in investigating the problem.
Mathieu NOE
2021-11-25
hello (again !)
a and b are tables - you cannot do directly
c=(a-b)./a
d=c*100
you can do it f you select elements from the tables
Pul
2021-11-25
Mathieu NOE
2021-11-26
hello @Pul
can you explain what is the intention ? the tables contain multiple columns so the math you want to do is for which ones ?
Pul
2021-11-30
采纳的回答
Star Strider
2021-11-26
0 个投票
Use the table2array function to convert the contents of the table to an array. Assign the arrays to new variables rather than over-writing the tables, since the references in the tables may be useful later in the code.
However the first column of the (40x13) table ‘DATIMARannuali’ is a year value (not a datetime array) with the variable name 'Year' so including that in the calculation may not be appropriate. While I did not download and open ‘DATA_ECM.mat’ the sizes of the two tables must match for tthe element-wise calculations to succeed, and the variables must be the same (or have similar contexts) for the calculation to make any sense.
.
更多回答（1 个）
Peter Perkins
2021-11-26
As StarStride hints, these tables are not even the same size, in either dimension:
>> DATIECMWFannuali
DATIECMWFannuali =
24×17 table
[snip]
>> DATIMARannuali
DATIMARannuali =
40×13 table
[snip]
If they were, there are a few ways to do this, all more or less syntactic variations on the same thing: a table is a container, and you need to do the math on the contents, not the container. As SS points out, one of the variables in these tables is a year number, and surely you dont want to include that in the calculation. So first, probably, convert to timetables.
Given that, the simplest thing would be something like
c = (DATIECMWFannuali.Variables-DATIMARannuali.Variables)./DATIECMWFannuali.Variables;
d = array2table(c*100,'VariableNames',DATIECMWFannuali.Properties.VariableNames);
or perhaps
a = DATIECMWFannuali.Variables; % or DATIECMWFannuali{:,:}, or table2array(DATIECMWFannuali)
b = DATIMARannuali.Variables; % or ...
c = (b-a)./a;
d = array2table(c*100,'VariableNames',DATIECMWFannuali.Properties.VariableNames);
If you leave them as tables, then probably the ...{:,:} syntax is easiest, because you can use ...{:,2:end}.
The whole topic of "doing math on data in tables" is explored here: "This example ... shows how to perform calculations by using the numeric and categorical data that the table contains." You might find that helpful.
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