recursive aggregating treetable and 3-d pivot table for hypergrid
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Getting Started



Click Events

Button Events

Scrolling and Update




Scripts and Contexts



Getting Started

Hypertree is a q server which adds tree- and pivot-table calculation to Hypergrid.

What follows is designed to teach you how to connect your data to Hypertree.

Hypertree uses either a one- or two-server configuration. The two-server model dedicates one server (s) to the data and the other (c) to the Hypergrid client. We'll concentrate on the simpler of the two configurations, in which a single server (h) manages the data as well as the event- and display-processing of the Hypergrid client.

The interface between Hypertree and your application is a single script, d.q. Hypertree comes equipped with a pre-defined d.q containing two examples. We'll focus on the first example, a pnl calcuator built on a trading simulation.

The example script contains two blocks of code.

The first block consists of the trading simulation itself, in which the necessary tables and functions are defined. One of those tables will serve as the underlying data of the Hypertree engine. In our example, the underlying table is called 'pnl', and we point Hypertree at it using the T configuration variable: T:`pnl.

The second block contains the Hypertree configuration variables, which map T to different properties and behaviors of the Hypertree engine. You can control the naming of the Hypertree table -- the treetable or pivot-cube -- by symbolic association. In this example, the Hypertree table is 'z', and we point Hypertree at it using the Z configuration variable: Z:`z.

Using indirection in this way allows the application to perform both pre- and post-processing on variables whose names it controls.

For the most part, Hypertree provides reasonable defaults for the configuration variables, but there are two which you must supply: the initial list of grouping columns G, and the initial list of aggregation columns F.

50 stock symbols:


At each simulation step, .5 percent of the traders will trade:


The raw trader table:


The raw stocks table:




We want to create virtual buckets consisting of unit-trader-strategy-symbol:

groups:{z,(1#x)!enlist(neg 1+rand count[y])?y}
traders:ungroup groups[`strategy;strategies]each traders
traders:ungroup groups[`symbol;exec symbol from stocks]each traders
traders:1!`id`unit`trader`strategy`symbol xcols update id:til count traders from traders

Trade at each time-step:

 m:floor per*c:count tr;
 i:exec id from tr where i in neg[m]?c;
 s:tr[flip enlist i;`symbol];
 p:(exec symbol!oprice from st)s;
 p+:(m?-1 0 1)*(m?.001)*p;
 q:(m?-1 1.)*100*1+m?10;
 o:select symbol:`HEDGE,first date,first time,price:5.0,qty:neg(sum price*qty)%5.0*0.9995 
  by id from r;

Trade, then calculate pnl:

 t:select trades:count id,qty:sum qty,cprice:last price,vwap:qty wavg price 
  by id,symbol from trades;
 u:(0!traders lj update real:qty*vwap,unreal:qty*cprice from t)lj stocks;
 pnl::update vwap:0n from(update"j"$qty,pnl:real+unreal from 
  select from u where not null qty)where vwap=0w;

Calculate the initial pnl:


Input and ouput tables:


Initial grouping columns:


Initial aggregated columns:


Show top 7 trader-earners within top 5 unit-earners:

J:([c:`unit`trader]s:`pnl`pnl;n:5 7;o:`a`a)

Filter pnl where qty>0:

V::exec i from pnl where qty>0

Do not show leaves of the pnl table:


Rollup calculations:


Default sorts = absolute-descending on the pnl column:


Display properties:


Updates are on; trade and recalculate pnl every 5 seconds:

\t 5000

Also see the section below on the general event processing callback E.


Hypertree uses an improved version of the algorithm described here.

Suppose our tree has the following structure:


Data-elements are attached to the leaves of the tree:

  2 - 20
  3 - 30
   6 - 60
   7 - 70
   8 - 80

Aggregations at the nodes are calculated iteratively, bottom-up:

0 = 2 + 3 + 6 + 7 + 8
1 = 2 + 3
4 = 5
5 = 6 + 7 + 8

The iterative method requires that we have in hand the ultimate constituents -- the leaves -- of each node:

0 : 2 3 6 7 8
1 : 2 3
4 : 5
5 : 6 7 8

We compute the leaves by first constructing the "parent vector" of our tree:

p:0 0 1 1 0 4 5 5 5

p[i] is the parent of element i:

q)p 5

Ascend from any leaf to the root node:

q)p 8
q)p 5
q)p 4

The root is self-parenting:

q)p 0
q)p p p p p p 0

Converge from any leaf to the root:

q)p over 8
q)p scan 8
8 5 4 0

Generate all paths from ultimate constituents:

q)i:(p scan)each til count p
1 0
2 1 0
3 1 0
4 0
5 4 0
6 5 4 0
7 5 4 0
8 5 4 0

The ultimate constituents:

q)l:til[count p]except p
2 3 6 7 8

Populate the leaves with data-elements:

0 0 20 30 0 0 60 70 80

and use the path-list to sum up from the leaves:

260 50 20 30 210 210 60 70 80

Hypertree provides support for user-defined aggregation functions, or "rollups". A rollup is a function which maps lists to atoms.

A companion utility, Hypercalc, provides a mechanism whereby the application can define calculated columns, or "willbes". A willbe is a function which maps lists of count n to lists of count n.

Together, Hypertree and Hypercalc can be used to define automatically recalculating hierarchical treetables and pivot-tables.

Hypertree pivot-tables are two-dimensional slices of a three-dimensional cube.

For this, we rely on a version of the function presented by Nick Psaris in his book Q-TIPS. Our version of Nick's function:

pcalc:{[t;z;y;x]?[t;();y!y,:();({x#(`$string y)!z}`$string asc distinct t x;x;z)]}  

The basic idea of a three-dimensional hierarchically nested pivot table -- a "pivot-cube" -- was first developed in the k2 algorithm here.

Conceptually, a pivot table is built from the unique values of two axes X and Y, where the cell z at the intersection of X and Y is an aggregation of a further column Z, a member of F.

In Hypertree pivot mode, we can visualize the aggregatable columns F to lie on the z axis, with the display showing one slice at a time. The Back and Forth buttons allow us to move back and forth on this axis, showing aggregations of the different columns in F.

In pivot mode, clicking on the down-triangle icon of the header of column A at value V will cause Hypertree to restrict the underlying table T to records where A = V, and then explode the X axis of the pivot to column B in G = .. A B .. .

Similarly, clicking on value V of column A in the Hierarchy column while in pivot mode will cause Hypertree to restrict the underlying table T to records where A = V, and then explode the Y axis of the pivot to column B in G = .. A B .. .

Double-clicking on a cell XY while in pivot mode is equivalent to performing a column pivot followed by a row pivot.

Finally, clicking on the up-triangle of the header of the Hierarchy column causes the last pivot action to be undone.

Hypertree thus provides drill-down interaction on both X, Y, and Z axes of a three-dimensional hierarchical pivot table.


Given the underlying table T + Hypertree parameters .ht.cons returns Z, the Hypertree table.

Column names beginning with a lower-case letter followed by one or more _'s are reserved for Hypertree use.

The Hypertree table structure is encoded in the six columns n_, e_, l_, o_, p_, and g_:

n_                          e_ l_ o_ p_ g_         
()                          0  0  1  0             
,`abbott                    0  1  0  0  abbott     
,`chico                     0  1  1  0  chico      
`chico`energy               0  2  0  2  energy     
`chico`financials           0  2  1  2  financials 
`chico`financials`chart     0  3  0  4  chart      
`chico`financials`house     0  3  0  4  house      
`chico`financials`indexarb  0  3  0  4  indexarb   

n_:  path to record
e_:  leaf?
l_:  level (0 = root, i>0 = child of i-1)
o_:  open?
p_:  parent vector
g_:  last each n_ (hierarchy column)

I_:  temporary variable used in sorting
J_:  temporary variable used in sorting
G_:  temporary variable used in sorting

Click Events

row:        in treetable mode, click on an element in the Hierarchy column to expand
            from or contract to that row.

            in pivot mode, click on an element in the Hierarchy column to select that
            row-value and explode on the next group.

col:        in treetable mode, click on a column to pivot the table on the column-value.

            in pivot mode, click on a column to select that column-value and explode on 
            the next group.

cell:       double-click on a cell to restrict the table to the row-value and pivot the 
            resulting table on the column-value.

sorts:      table multi-sort.

            symbol and character columns have case-insensitive ascending (a) and
            descending (d).

            columns of other types have ascending (a), descending (d), ascending-
            absolute (A), and descending-absolute (D).

groups:     press the alt/option key to summon the column-arrangement window which 
            allows drag-and-drop regrouping of the table, and selection of visible/
            invisible columns.

            columns may also be re-arranged directly with drag-and-drop.

Button Events

Reset:      clear sorts, expansions, pivots, &c.

Expand:     expand the tree to the level of the last group.

Collapse:   collapse the tree to the level of the first group.

Back:       Pick the previous column on the z-axis to pivot on.

Forth:      Pick the next column on the z-axis to pivot on.

Swap:       in treetable mode, swap G 0 and G 1:  G = x y .. z -> y x .. z

            in pivot mode, swap X and Y:  X Y -> Y X

Up:         rotate group-vector:  G = x y .. z -> z x y ..

Down:       rotate group-vector:  G = x y .. z -> y .. z x

Pause:      turn updates off.

Play:       turn updates on.

Scrolling and Update

On scrolling, Hypergrid requests a subtable of Z:

get:        send a subtable of the current state of Z to Hypergrid.

Hypertree also supports update. For example, if the underlying table is t:

\t 1000
.z.ts:{update ... from `t ...;.hg.upd`}

This causes Hypertree to recalculate and redisplay.

Note that Hypertree will recalculate the hierarchy based on both aggregating and grouping columns.

Hypercalc can also be used to define automatically recalculating underlying views.


Hypertree behavior is controlled by a set of programmer-defined global variables.

Dependencies (*var::def) are internal functions and should not be redefined. Other variables may be initialized on startup as part of d.q.

The following variables must be defined by the application:

G (unless there are no grouping columns)
T (unless the underlying table = t)
Z (unless the underlying table = z)

All other variables default to reasonable values.

A: Rollups

Rollup expressions are q parse-trees:


Hypertree will use sensible defaults (e.g. sum for numeric.)

Multiple rollups can be defined for a single column:


Rollup functions map lists to atoms.  If the type of column c is t, then the
type of the rollup of c must be -t.

Columns defined in A which do not appear in T are "virtual":  their leaves are
displayed as nulls.  E.g., in the following example g is virtual:

    t:([]f:10 20 30)

'parse' can used to define complex rollup expressions:

    A[`k]:parse"sum[l]+sum m"

B: NYI: Reserved for incremenetal update functions

*C: Visible columns[Q;G]I

D: Data function


If D is defined as a (result-returning) monadic function:

    output-string <- D input-string

then two rows are manifested in the Hypertree window, one for input, one for output.

The string typed into the input row is passed to D, and the result of D is written 
into the output row.

E: Event function


E is called on every Hypertree event.  By default it takes and returns the result of
Hypertree processing.  For example, define E as E:0N! then click to expand a row.

E provides a simple mechanism for connecting Hypertree events to the application
in which it is embedded.

F: Visible columns in order


G: Grouping columns in order


Any subset of exec c from meta T where t in"bhijspmdznuvt".

Keys of the underlying table are not groupable.

Hypertree understands grouping by symbolic and "discrete" values (including dates and 

When G is empty, the underlying table together with its grand total row is displayed:

*H: Groupable columns T 

*I: Invisible columns[W;T;A;Q;F]G

J: Ordering (top or bottom n)


For example, to see just the seven units with the highest pnl, and within each of
those, the top five traders with the highest pnl:

    J:([c:`unit`trader]s:`pnl`pnl;n:5 7;o:`a`a)

The selection is performed on T *before* Z is calculated, so the totals in Z do not
reflect absolute totals in T.

K: Sort vector

Hypertree sort-state:  get[Z]K.


L: Expand to leaves?


By default, Hypertree expands to display the leaves of the treetable.  If this behavior
is not desired (for example, because there are too many ultimate records, or because the
data at the leaves is not interesting), set L to 0b.

M: Not used

*N: Row count

N::count get T

O: Object properties


Display properties can be coordinated between Hypertree and Hypergrid with the multi-level 
dictionary O.  For example:


O is designed as a completely general way to put Hypergrid display characteristics under
the control of the Hypertree application program.

Consult the Hypergrid documentation for a full description of this feature.

P: Instruction state = (current;prior)

The state of the Hypertree is represented as a pair of keytables.  P 0 represents the 
current state, and P 1 represents the previous state.  n (the key) is a list of paths to
nodes which have at any time been opened, and v is a boolean vector saying whether the 
corresponding node is now open or closed.

For example:

q)P 0
n                                             | v
----------------------------------------------| -
(`symbol$())!()                               | 1
(,`trader)!,`costello                         | 0
`trader`sector!`costello`energy               | 1
`trader`sector`strategy!`costello`energy`house| 1

q)P 1
n                                             | v
----------------------------------------------| -
(`symbol$())!()                               | 1
(,`trader)!,`costello                         | 1
`trader`sector!`costello`energy               | 1
`trader`sector`strategy!`costello`energy`house| 1

*Q: q-types get Z

Q is a dictionary of q-types by column.  For example, Q.N = "j".

R: Rows -> Hypergrid (scrolling)

R:`start`end!0 100

S: Sorts = cols!(..{adAD}..)


a = ascending (case-insensitive for char/sym)
d = descending (case insensitive for char/sym)
A = ascending absolute (non-char/sym)
D = descending absolute (non-char/sym)

For example:  S:`foo`bar!`D`a for ascending bar within descending-absolute foo.

T: Table

The table underlying Hypertree, either keyed or unkeyed.


U: Update?


If U is null, do not show Pause or Play buttons.

If U is boolean, then Play (1b) or Pause (0b) updates.

To update Hypertree, use:


For example,


V: View


V can be an index vector (type 6 or 7), e.g.

    V::exec i from pnl where qty>0

or a function (type > 99), e.g.

    V:{select from x where qty>0}

W: Pivot state = (();();();())

W[0] = (pivot column;value of Q for T)
W[1] = (..;(=;column;value);..)                 list of constraint expressions
W[2] = (..;previous value of G;..)              list of group vectors
W[3] = (..;previous value of S;..)              list of sort dictionaries

Pivot and Y Axis drill-down operations are mutually exclusive.

W keeps track of the sequence of pivot operations, and allows the user to unwind from the 
current to the previous pivot-state.  

Note that the application (d.q) can define an initial state for W.

*X: X axis

X::$[count W 1;first 1_G except W[1;;1];G 1]

*Y: Y axis

Y::G 0

Z: Hypertree


Z is symmetrical with T:  a pointer to the Hypertree result-table.


Hypertree calculates rollups on every Y-axis drilldown event, and on every X- or XY-pivot event, and on every update to the underlying data.


Single process:

Start hypertree process (default port 12345, \t = 0):

    cd hypertree
    q h.q

The one-process version single-threads q updates and Hypergrid interaction.


Start hypertree client (default port 12345):

    cd hypertree
    q c.q

Start hypertree server (default port 12346):

    cd hypertree
    q s.q

Client and server processes may be started in either order.

The two-process version decouples q update and Hypergrid interaction.

By default, both client and server start on the same host.

After starting either the single process or the two-process version of Hypergrid, start Hypergrid.

Scripts and Contexts

q.q             enhance json to filter infinities
d.q             data and parameter definition
e.q             hypergrid events
t.q             hypertree calculation
i.q             initial state (used by reset)
j.q             javascript interaction utilities
x.q             hypertree parameters
a.q             auxiliary functions

h.q             standalone hypertree process

c.q             hypertree client process
s.q             hypertree server process

.hg             hypergrid context
.ht             hypertree context
.hc             hypercalc context
.               hypertree parameters A .. Z, A_ .. Z_


The coding style of Hypertree assumes that both client and server processes are detached from the application which uses them. That is, h.q, c.q, and s.q are only executed via q h.q, q c.q, or q s.q, as opposed to being directly loaded into the application with \l.

The d.q script is the API for hypertree, through which the application environment is presented to Hypertree by means of some combination of \l, file-reads, and interprocess communication.

For this reason, the Hypertree parameters are defined in the root context as global variables A .. Z, and a subset of A_ .. Z_.


The initial release of Hypertree supports treetable- and pivot-cube drilldown on a single input table T. In what follows I will describe how this structure can be extended in several useful ways.

There are two types of Hypertree instance: a single process h, and a pair of communicating processes s and c, where s manages the data and update-events and c manages client-events.

Think of a Hypertree instance of either type as a function taking T and the parameters A, B, C .. and returning Z. Events such as updates, clicks, drag-and-drops and button-clicks cause Z to be recomputed.

I think of this system as a dynamic view of T. So currently we have one view of one table per Hypertree instance.

We can imagine extending a single Hypertree instance in two ways:

  • Multiple views

For example, Z1 and Z2 are different views of T. In Z1 we have F = F1, G = G1, &c., and in Z2 we have F = F2, G = G2, &c. In other words, we allow distinct independent sets of configuration variables.

  • Multiple tables

For example, Z1 is a view of T1 and Z2 is a view of T2.

  • Multiple instances

We can also imagine extending Hypertree to support multiple communicating instances. For example, if T1 and T2 are too large to fit comfortably in a single process of either the h or s type, or if calculation of multiple views is too expensive to permit responsive operation of the client h or c, we might want to implement our multi-view or multi-table design using multiple instances of Hypertree. We are free to use as many instances as necessary, and to freely distribute tables and views among them. (how we represent this structure in the gui is left open: as tabs, as elements in dashboards, nested, tiled, &c.)

Whether we use a single- or multiple-instance design we can define a linking operation on multiple views, which can be represented this way:

Z1 -> f=a -> Z2

which means:

compute Z2 from: V2 & select from T2 where f=a

where V2 is the filter used to compute Z2 from T2.

  • Condense Z planes

In a future version of Hypertree we will support "super-cells" containing multiple z values by condensing selected planes of the pivot cube.

  • Show the X axis as a transposed tree

  • Zoomable/scalable fonts based on depth of the tree or pivot-cube

  • Inline rollup-function editor

  • Incremental updates

Updates to T trigger total recalculation of the hypertree. But for some aggregation functions a in A we can imagine supplying b in B which avoid recalculation from the leaves. For example, if a = sum x, then b would calculate the quantity to add to or subtract from each aggregation of x and apply those changes selectively.

  • Functional generalization of drilldown

For example, select precalculated "totals" from auxiliary subtables to avoid recalculation of non-updating tables.

  • Static rollups

Implemented in an earlier version of Hypertree, but removed until a good use-case can be found.

Create a dictionary whose keys are a subset of the permutations of G.

sector   strategy trader  | :../t/sector.strategy.trader
sector   trader   strategy| :../t/sector.trader.strategy
strategy sector   trader  | :../t/strategy.sector.trader
strategy trader   sector  | :../t/strategy.trader.sector
trader   sector   strategy| :../t/trader.sector.strategy
trader   strategy sector  | :../t/trader.strategy.sector

Then in d.q:

T:(`t;.af.get`:t)   (OR:`:t;T:`t`u)

u is a dictionary whose keys are drawn from the permutations g of G and whose values 
are symbols of, or the actual complete rollup trees for t and each g.