pygplates.GpmlKeyValueDictionary

class pygplates.GpmlKeyValueDictionary

Bases: pygplates.PropertyValue

A dictionary of key/value pairs that associates string keys with integer, float or string values.

This is typically used to store attributes imported from a Shapefile so that they are available for querying and can be written back out when saving to Shapefile.

The following operations are supported:

Operation	Result
`len(d)`	number of elements in dictionary d
`for k in d`	iterates over the keys k in dictionary d
`k in d`	`True` if k is a key in dictionary d
`k not in d`	`False` if k is a key in dictionary d

For example:

for key in dictionary:
    value = dictionary.get(key)

The following methods support getting, setting and removing elements in a dictionary:

get()
set()
remove()

__init__([key_value_mapping])

Create a dictionary containing zero or more key/value pairs.

Parameters: key_value_mapping (dict mapping each key (string) to a value (integer, float or string), or a sequence of (key, value) tuples, or None) – optional mapping of keys to values

To create an empty dictionary:

dictionary = pygplates.GpmlKeyValueDictionary()

To create a dictionary with two key/value pairs:

dictionary = pygplates.GpmlKeyValueDictionary(
    [('name', 'Test'), ('id', 23)])

To do the same thing using a dict:

dictionary = pygplates.GpmlKeyValueDictionary(
    {'name' : 'Test', 'id' : 23})

Methods

`__init__`([key_value_mapping])	Create a dictionary containing zero or more key/value pairs.
`accept_visitor`(visitor)	Accept a property value visitor so that it can visit this property value.
`clone`()	Create a duplicate of this property value (derived) instance, including a recursive copy of any nested property values that this instance might contain.
`get`(key, [default_value])	Returns the value of the dictionary element associated with a key.
`get_geometry`()	Extracts the `geometry` if this property value contains a geometry.
`get_value`([time=0])	Extracts the value, of this possibly time-dependent property value, at the reconstruction time.
`remove`(key)	Removes the dictionary element associated with a key.
`set`(key, value)	Sets the value of the dictionary element associated with a key.

get(key[, default_value])

Returns the value of the dictionary element associated with a key.

Parameters

key (string) – the key of the dictionary element
default_value (int or float or string or None) – the default value to return if the key does not exist in the dictionary (if not specified then it defaults to None)

Returns

the value associated with key, otherwise default_value if key does not exist

Return type

integer or float or string or type(default_value) or None

To test if a key is present and retrieve its value:

value = dictionary.get('key')
# Compare with None since an integer (or float) value of zero, or an empty string, evaluates to False.
if value is not None:
...
# ...or a less efficient approach...
if 'key' in dictionary:
    value = dictionary.get('key')

Return the integer value of the attribute associated with ‘key’ (default to zero if not present):

integer_value = dictionary.get('key', 0)

remove(key)

Removes the dictionary element associated with a key.

Parameters: key (string) – the key of the dictionary element to remove

If key does not exist in the dictionary then it is ignored and nothing is done.

set(key, value)

Sets the value of the dictionary element associated with a key.

Parameters

key (string) – the key of the dictionary element
value (integer, float or string) – the value of the dictionary element

If there is no dictionary element associated with key then a new element is created, otherwise the existing element is modified.