I use a structure called test
with the following "layout" (result of whos test, test
)
Name Size Bytes Class Attributes
test 1x1 8449048 struct
test =
timestamp: {[7.3525e+05] [7.3525e+05] [7.3525e+05]}
timeseries: {[44000x8 double] [44000x8 double] [44000x8 double]}
For speed issues, I want to preallocate that with zeros. I found some ways, which result in other "layouts":
test2=struct('timestamp',cell(1,3),'timeseries',cell(1,3));
test3=struct('timestamp',{0,0,0},'timeseries',{zeros(44000,8),zeros(44000,8),zeros(44000,8)});
tempstamp={0,0,0};
tempseries={zeros(44000,8),zeros(44000,8),zeros(44000,8)};
test4=struct('timestamp',tempstamp,'timeseries',tempseries);
whos test2 test3 test4,test2,test3,test4
resulting in
Name Size Bytes Class Attributes
test2 1x3 176 struct
test3 1x3 8448824 struct
test4 1x3 8448824 struct
test2 =
1x3 struct array with fields:
timestamp
timeseries
test3 =
1x3 struct array with fields:
timestamp
timeseries
test4 =
1x3 struct array with fields:
timestamp
timeseries
When issuing the commands test5.timestamp=tempstamp;test5.timeseries=tempseries;whos test5,test5
one gets
Name Size Bytes Class Attributes
test5 1x1 8449048 struct
test5 =
timestamp: {[0] [0] [0]}
timeseries: {[44000x8 double] [44000x8 double] [44000x8 double]}
Thus reproducing the "layout" in test
. This is strange, isn't it?
Further using test2.timestamp{2}=now
is not working as with test3
and test4
.
Okay, this is described in the documentation help struct
, but how can I preallocate such 1x1 struct
like test
or test5
within one line? Best without those temp*
variables.
Using struct
with cells to init a field with cell requires depth-2 cell:
test=struct('timestamp',{cell(1,3)},'timeseries',{cell(1,3)});
or
test3 = struct( 'timestamp', { {0,0,0}},...
'timeseries',{ {zeros(44000,8),zeros(44000,8),zeros(44000,8)} });
For reference see struct
doc the example regarding "Fields that Contain Cell Arrays".