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"result = expression"
As default, topological relationships between space time datasets will be evaluated only temporal. Use the s flag to activate the additionally spatial topology evaluation.
The expression option
must be passed as quoted expression, for example:
t.select expression="C = A : B"
equals A ------
B ------
during A ----
B ------
contains A ------
B ----
starts A ----
B ------
started A ------
B ----
finishs A ----
B ------
finished A ------
B ----
precedes A ----
B ----
follows A ----
B ----
overlapped A ------
B ------
overlaps A ------
B ------
over booth overlaps and overlapped
Topological relations must be specified in {} parentheses.
LEFT REFERENCE l Use the time stamp of the left space time dataset INTERSECTION i Intersection DISJOINT UNION d Disjoint union UNION u Union RIGHT REFERENCE r Use the time stamp of the right space time dataset
C = A : B
In addition the inverse selection operator !: is defined as the complement of the selection operator, hence the following expression
C = A !: B
To select parts of a STDS by different topological relations to other STDS, the temporal topology selection operator can be used. The operator consists of the temporal selection operator, the topological relations, that must be separated by the logical OR operator | and the temporal extent operator. All three parts are separated by comma and surrounded by curly braces:
{"temporal selection operator", "topological relations", "temporal operator"}
Examples:
C = A {:, equals} B
C = A {!:, equals} B
C = A {:,equals|during|overlaps} B
C = A {:, during,r} B
The selection operator is implicitly contained in the temporal topology selection operator, so that the following statements are exactly the same:
C = A : B
C = A {:} B
C = A {:,equal} B
C = A {:,equal,l} B
C = A !: B
C = A {!:} B
C = A {!:,equal} B
C = A {!:,equal,l} B
if statement decision option temporal relations if(if, then, else) if(conditions, A) A if conditions are True; temporal topological relation between if and then is equal. if(conditions, A, B) A if conditions are True, B otherwise; temporal topological relation between if, then and else is equal. if(topologies, conditions, A) A if conditions are True; temporal topological relation between if and then is explicit specified by topologies. if(topologies, conditions, A, B) A if conditions are True, B otherwise; temporal topological relation between if, then and else is explicit specified by topologies.
Symbol description == equal != not equal > greater than >= greater than or equal < less than <= less than or equal && and || or
td(A) Returns a list of time intervals of STDS A start_time(A) Start time as HH::MM:SS start_date(A) Start date as yyyy-mm-DD start_datetime(A) Start datetime as yyyy-mm-DD HH:MM:SS end_time(A) End time as HH:MM:SS end_date(A) End date as yyyy-mm-DD end_datetime(A) End datetime as yyyy-mm-DD HH:MM start_doy(A) Day of year (doy) from the start time [1 - 366] start_dow(A) Day of week (dow) from the start time [1 - 7], the start of the week is Monday == 1 start_year(A) The year of the start time [0 - 9999] start_month(A) The month of the start time [1 - 12] start_week(A) Week of year of the start time [1 - 54] start_day(A) Day of month from the start time [1 - 31] start_hour(A) The hour of the start time [0 - 23] start_minute(A) The minute of the start time [0 - 59] start_second(A) The second of the start time [0 - 59] end_doy(A) Day of year (doy) from the end time [1 - 366] end_dow(A) Day of week (dow) from the end time [1 - 7], the start of the week is Monday == 1 end_year(A) The year of the end time [0 - 9999] end_month(A) The month of the end time [1 - 12] end_week(A) Week of year of the end time [1 - 54] end_day(A) Day of month from the start time [1 - 31] end_hour(A) The hour of the end time [0 - 23] end_minute(A) The minute of the end time [0 - 59] end_second(A) The second of the end time [0 - 59]
{"comparison operator", "topological relations", aggregation operator, "temporal operator"}
|| -> | and && -> &
Condition 1 {||, equal, r} Condition 2
Condition 1 {&&, equal|during, l} Condition 2
Condition 1 {&&, equal|contains, |, l} Condition 2
Condition 1 {&&, equal|during, l} Condition 2 && Condition 3
Condition 1 {&&, equal|during, l} Condition 2 {&&,contains, |, r} Condition 3
A{#, contains}B
C = if({equal}, A {#, contains} B > 2, A {:, contains} B)
Furthermore the temporal algebra allows temporal buffering, shifting and snapping with the functions buff_t(), tshift() and tsnap() respectively.
buff_t(A, size) Buffer STDS A with granule ("1 month" or 5)
tshift(A, size) Shift STDS A with granule ("1 month" or 5)
tsnap(A) Snap time instances and intervals of STDS A
tmap()
C = A {:,during} tmap(event)
Boolean Name Operator Meaning Precedence Correspondent function ---------------------------------------------------------------------------------- AND & Intersection 1 (v.overlay operator=and) OR | Union 1 (v.overlay operator=or) DISJOINT OR + Disjoint union 1 (v.patch) XOR ^ Symmetric difference 1 (v.overlay operator=xor) NOT ~ Complement 1 (v.overlay operator=not)
buff_p(A, size) Buffer the points of vector map layer A with size buff_l(A, size) Buffer the lines of vector map layer A with size buff_a(A, size) Buffer the areas of vector map layer A with size
{"spatial or select operator" , "list of temporal relations", "temporal operator" }
For multiple topological relations or several related maps the spatio-temporal operators feature implicit aggregation. The algebra evaluates the stated STDS by their temporal topologies and apply the given spatio temporal operators in a aggregated form. If we have two STDS A and B, B has three maps: b1, b2, b3 that are all during the temporal extent of the single map a1 of A, then the following overlay calculations would implicitly aggregate all maps of B into one result map for a1 of A:
C = A {&, contains} B --> c1 = a1 & b1 & b2 & b3
C = B {&, during} A --> c1 = b1 & a1
c2 = b2 & a1
c3 = b3 & a1
D = if(start_date(A) < "2005-01-01", A & B)
D = buff_p(A, 1) {&,overlaps|overlapped|equal|during|contains,i} buff_p(B, 1)
D = if(contains, td(buff_t(A, "1 days")) == 3, B, C)
Available at: t.vect.algebra source code (history)
Latest change: Wednesday Nov 25 02:25:37 2020 in commit: 44c12764d2a84ebe36ab199d115395d095730390
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