extractfield
Field values from structure array
Syntax
Description
Examples
Load a structure that contains information about roads in Concord, MA.
roads = shaperead('concord_roads.shp');
r = roads(1:5);
Get the x- and y-coordinates of the roads. Display the map, and highlight the first few elements using the color magenta.
hold on plot(extractfield(roads,'X'),extractfield(roads,'Y')); plot(extractfield(r,'X'),extractfield(r,'Y'),'m');
Extract the names of the roads, stored in the field STREETNAME
. The field values are character vectors, so the result is returned in a cell array.
names = extractfield(r,'STREETNAME');
Extract the X
field from the structure and examine the format of the returned values. All values have the same numeric data type (double
), so the result is returned in a vector.
uniformType = extractfield(r,'X');
For illustrative purposes, change the X field value in one of the elements to have a different data type. This command converts the second element to data type single
.
r(2).X = single(r(2).X);
Extract the X
field values again. This time, the values have different data types, so the result is returned in a cell array.
mixedType = extractfield(r,'X');
Input Arguments
Structure, specified as a structure.
Field name, specified as a case-sensitive string scalar or character vector.
Output Arguments
Extracted field values, returned as a 1-by-n numeric
vector or cell array. n is the total number of elements
in the field name
of structure S
,
that is, n = numel([S(:).(name)])
. a
is a cell array if any field values in the field name contain a character
vector or if the field values are not uniform in type; otherwise
a
is the same type as the field values. The shape
of the input field is not preserved in a
.
Version History
Introduced before R2006a
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