Convert Columns Arrays to numeric

Question

Stefan Azzopardi 2020-1-15

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/500377-convert-columns-arrays-to-numeric

回答： Steven Lord 2020-1-15

Hi,

I have a timetable with various data columns - I have imported these from an excel file. I need to make an addition to the all rows of colums and to add a column with the result. I think that my arrays are currently not numeric type and therefor I can not add them. Is there a way that I can convert data of columns 1-7 to numeric and make a summation? Or how can I know the data type of the columns?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Andrei Bobrov 2020-1-15

在 MATLAB Online 中打开

Please attach here your variable 'combine' as mat-file

>> save('yourdata.mat','combine') % run in yur Command Window

And attach here file yourdata.mat .

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Andrei Bobrov 2020-1-15

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/500377-convert-columns-arrays-to-numeric#answer_410211

编辑：Andrei Bobrov 2020-1-15

在 MATLAB Online 中打开

data.mat

...how can I know the data type of the columns?

varfun(@class,combine)

solution:

load('data.mat')
combine = [combine,rowfun(@funsum,combine,'OutputVariableName','SUM_ALL_kW')];
function out = funsum(varargin)
    out = sum([varargin{:}],2);
end

or

combine.SUM_ALL_kW = sum(combine{:,:},2) ;

2 个评论
显示无隐藏无

Andrei Bobrov 2020-1-15

Comment by Stefan Azzopardi:

Andrei, Thanks for your help and it worked perfectly. This resulted in a new column with the sum of the other columns. Thank you once again for your help :) :)

Andrei Bobrov 2020-1-15

Stefan! If my answer solved your problem, then please accept it.

请先登录，再进行评论。

Answer 2

WalterWhite 2020-1-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/500377-convert-columns-arrays-to-numeric#answer_410203

t = datetime('now')

nn = datenum(t)+10;

f= datetime(nn,'ConvertFrom','datenum')

>> reading

t =

datetime

15-Jan-2020 09:52:43

f =

datetime

25-Jan-2020 09:52:43

did you mean something like this?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Stefan Azzopardi 2020-1-15

thank you for your help Walter, but it is not exactly what I meant. Anyway, I got all the help that I requested from Andrei :) :)

请先登录，再进行评论。

Answer 3

Steven Lord 2020-1-15

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/500377-convert-columns-arrays-to-numeric#answer_410255

在 MATLAB Online 中打开

Using the example from the timetable help text:

MeasurementTime = datetime({'2015-12-18 08:03:05';'2015-12-18 10:03:17';'2015-12-18 12:03:13'});
Temp = [37.3;39.1;42.3];
Pressure = [30.1;30.03;29.9];
WindSpeed = [13.4;6.5;7.3];
WindDirection = categorical({'NW';'N';'NW'});
TT = timetable(MeasurementTime,Temp,Pressure,WindSpeed,WindDirection)

Let's say that I wanted (for whatever reason) to add the temperature, pressure, and wind speed. I can extract that data from TT into a numeric array in two different ways:

A1 = TT{:, ["Temp", "Pressure", "WindSpeed"]} % Using variable names
A2 = TT{:, 1:3} % Using variable numbers

Now sum and put back into TT.

TT.combinedData = sum(A1, 2)

If all your data could be concatenated into an array with a uniform type, you could extract the data even easier. But this technique won't work for TT, as you can't combine a numeric variable like TT.Temp and a categorical variable like TT.WindDirection into one array.

TT.Variables