# Sum of array items into another array

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np on 22 Jun 2016
Commented: Shameer Parmar on 24 Jun 2016
I need to find the sum of items within each of the 360 arrays and then make another array with just the sums.

Kirby Fears on 22 Jun 2016
np,
You indicated the data is in your workspace as data.speed1, data.speed2, etc.
In your workspace window, what is the data type of "data"? If it has fields speed1, speed2, etc, then "data" must be a table or struct. Please let me know which type it is so I can help.
np on 22 Jun 2016
the speed1 speed2 are just the names of the arrays that are there
the values inside of them are numeric
Kirby Fears on 22 Jun 2016
I understand that the values inside of speed1 and speed2 are numeric, but you wrote your example as "data.speed1". So are speed1 and speed2 contained in a workspace variable called data or not?

Kirby Fears on 22 Jun 2016
Assuming data is a struct with fields speed1, speed2, etc.
sumArray = structfun(@sum,data);

Guillaume on 23 Jun 2016
If your structure has fields other than the speed fields, you can loop over a hardcoded number of speed fields:
numspeed = 360;
speedsum = zeros(numspeed, 1);
for speedidx = 1:numspeed
speedsum(speedidx) = sum(data.(sprintf('speed%d', speedidx)));
end

Shameer Parmar on 23 Jun 2016
for i=1:length(fields(data))
s(i) = sum(eval(['data.speed',num2str(i)]));
end

np on 23 Jun 2016
i used:
for i=1:length(fields(data))
s(i) = sum(data.(['speed',num2str(i)]));
end
Guillaume on 23 Jun 2016
1) Use fieldnames instead of fields. That won't solve the immediate problem as they both provide the same result, but fields is not supported whereas fieldnames is.
2) You get this error because your data has fields other than the 360 speed fields.
Shameer Parmar on 24 Jun 2016
Hello np..
I guess your length of fields(data) is more that 360, that why..
If yes, you can apply one more filter like..
for i=1:length(fields(data))
if i<=360
s(i) = sum(data.(['speed',num2str(i)]));
end
end