class histogrammar.primitives.bag.Bag(quantity, range)[source]

Bases: histogrammar.defs.Factory, histogrammar.defs.Container

Accumulate raw numbers, vectors of numbers, or strings, with identical values merged.

A bag is the appropriate data type for scatter plots: a container that collects raw values, maintaining multiplicity but not order. (A “bag” is also known as a “multiset.”) Conceptually, it is a mapping from distinct raw values to the number of observations: when two instances of the same raw value are observed, one key is stored and their weights add.

Although the user-defined function may return scalar numbers, fixed-dimension vectors of numbers, or categorical strings, it may not mix range types. For the purposes of Label and Index (which can only collect aggregators of a single type), bags with different ranges are different types.


Add two containers of the same type. The originals are unaffected.

__init__(quantity, range)

Create a Bag that is capable of being filled and added.


quantity (function returning a float, a tuple of floats, or a str) – computes the quantity of interest from the data.

Other Parameters:
  • entries (float) – the number of entries, initially 0.0.
  • values (dict from quantity return type to float) – the number of entries for each unique item.
  • range (“N”, “N#” where “#” is a positive integer, or “S”) – the data type: number, vector of numbers, or string.

List of sub-aggregators, to make it possible to walk the tree.


Copy this container, making a clone with no reference to the original.

static ed(entries, values, range)

Create a Bag that is only capable of being added.

  • entries (float) – the number of entries.
  • values (dict from float, tuple of floats, or str to float) – the number of entries for each unique item.
  • range ("N", "N#" where "#" is a positive integer, or "S") – the data type: number, vector of numbers, or string.

Reference to the container’s factory for runtime reflection.

fill(datum, weight=1.0)

Increment the aggregator by providing one datum to the fill rule with a given weight.

Usually all containers in a collection of histograms take the same input data by passing it recursively through the tree. Quantities to plot are specified by the individual container’s lambda functions.

The container is changed in-place.


User’s entry point for reconstructing a container from JSON text.

static fromJsonFragment(json, nameFromParent)

staticmethod(function) -> method

Convert a function to be a static method.

A static method does not receive an implicit first argument. To declare a static method, use this idiom:

class C: def f(arg1, arg2, ...): ... f = staticmethod(f)

It can be called either on the class (e.g. C.f()) or on an instance (e.g. C().f()). The instance is ignored except for its class.

Static methods in Python are similar to those found in Java or C++. For a more advanced concept, see the classmethod builtin.

static ing(quantity)

Synonym for __init__.


Name of the concrete Factory as a string; used to label the container type in JSON.

plot(httpServer=None, **parameters)

Generate a VEGA visualization and serve it via HTTP.


Add a new Factory to the registry, introducing a new container type on the fly. General users usually wouldn’t do this, but they could. This method is used internally to define the standard container types.


Explicitly invoke histogrammar.specialized.addImplicitMethods on this object, usually right after construction (in each of the methods that construct: __init__, ed, ing, fromJsonFragment, etc).

Objects used as default parameter arguments are created too early for this to be possible, since they are created before the histogrammar.specialized module can be defined. These objects wouldn’t satisfy any of addImplicitMethod‘s checks anyway.


Return a copy of this container as though it was created by the ed function or from JSON (the “immutable form” in languages that support it, not Python).


Convert this container to dicts and lists representing JSON (dropping its fill method).

Note that the dicts and lists can be turned into a string with json.dumps.


Used internally to convert the container to JSON without its "type" header.


Create an empty container with the same parameters as this one. The original is unaffected.