stamp | R Documentation |
This function generates a sf
polygons object that can be used for spatial temporal analysis of moving polygons
as described in the paper Robertson et al. (2007).
stamp(T1, T2, dc = 0, direction = FALSE, distance = FALSE, ...)
T1 |
a |
T2 |
a |
dc |
spatial distance threshold for determining groupings (see Details) in appropriate units. |
direction |
logical, whether or not to perform directional analysis. See documentation for
|
distance |
logical, whether or not to perform distance analysis. See documentation for
|
... |
additional parameters to be passed to functions if |
The stamp
function can be used to perform spatial temporal analysis of moving polygons (STAMP)
as outlined in the paper by Robertson et al., (2007). Polygon movement "groups" are delineated based on
polygon connectedness defined by the distance threshold dc
. That is, if polygon
boundaries (in T1 or T2) are within distance dc
of one another they will be designated
to the same group. STAMP events are reported at four levels of increasing complexity:
LEV1 – disappearance (DISA
), stable (STBL
), and generation (GENA
);
LEV2 – disappearance (DISA
), contraction (CONT
), stable (STBL
),
expansion (EXPN
), and generation (GENR
);
LEV3 – disappearance (DISA
), T1 displacement (DISP1
), convergence (CONV
),
concentration (CONC
), contraction (CONT
), stable (STBL
),
expansion (EXP
), fragmentation (FRAG
), divergence (DIV
),
T2 displacement (DISP2
), and generation (GENR
);
LEV4 – LEV4 is different from other levels. It is used to identify those groups where
union (UNION
), division (DIVISION
), and both union and division
(BOTH
) events occur. These events occur when there are more than one
stable event in a group. Groups with one or no stable events receive an NA
value for LEV4.
See Robertson et al. (2007; especially Figure 1) for complete descriptions of all STAMP movement
event types.
Note also that there must be a unique ID of each polygon, the function uses the row.names of the polygon objects. Modify the row.names accordingly if you wish to use an alternative ID label.
This function returns a sf
polygons object with the following data columns:
ID1 |
Polygon ID from T1 polygons; |
ID2 |
Polygon ID from T2 polygons; |
LEV1 |
Level 1 STAMP designation, |
LEV2 |
Level 2 STAMP designation, |
LEV3 |
Level 3 STAMP designation, |
LEV4 |
Level 4 STAMP designation, |
GROUP |
Group ID signifying group membership, |
AREA |
Polygon area in appropriate areal units, |
– |
(optional) Additional columns from directional analysis if |
– |
(optional) Additional columns from distance analysis if |
Robertson, C., Nelson, T., Boots, B., and Wulder, M. (2007) STAMP: Spatial-temporal analysis of moving polygons. Journal of Geographical Systems, 9:207-227.
stamp.direction stamp.distance stamp.map stamp.group.summary
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