Problem with direct calculation on table with std and "omitnan"
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Jean-Marie Sainthillier
el 17 de Mayo de 2023
Respondida: Steven Lord
el 13 de Ag. de 2024 a las 17:39
Since R2023a, it is possible to perform calculations directly on tables (and timetables) without extracting their data by indexing.
I want use std directly on a numeric table where I can have nan.
For example :
load patients
T = table(Age,Height,Weight,Systolic,Diastolic)
mean(T,"omitnan")
It's fine.
But why there is a problem with std(T,"omitnan") ?
% Applying the function 'std' to the variable 'Age' generated an error.
I can use std(T{:,:},"omitnan") or std(T.Variables,"omitnan") but I lost the possibility to work directly with my table.
Did I miss something ?
Do you have any suggestion ?
Thank you in advance.
SAINTHILLIER Jean Marie
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Respuesta aceptada
Star Strider
el 17 de Mayo de 2023
Example —
load patients
T = table(Age,Height,Weight,Systolic,Diastolic)
S = varfun(@(x)std(x,'omitnan'),T)
.
3 comentarios
Keith Goatman
el 13 de Ag. de 2024 a las 9:15
I too was caught out by the inconsistent behaviour of mean and std on tables in 2024a. The answer above works around it but it doesn't explain why they should behave differently.
Más respuestas (1)
Steven Lord
el 13 de Ag. de 2024 a las 17:39
This looks like a bug to me. It seems that std for table arrays assumes that if you're passing the missingflag input that you've also specified the normalization option or weights. But specifying just the data and the missingflag input is a supported syntax for a double array input and so probably should be supported for a table array input.
A workaround is to specify the default normalization option (0) in the std call as the second input.
load patients
T = table(Age,Height,Weight,Systolic,Diastolic);
mean(T,"omitnan")
std(T, 0, "omitnan")
% check
std(T.Age, "omitnan")
I'll report this to the development staff.
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