# cf.Field.cell_measure¶

Field.cell_measure(identity=None, default=ValueError(), key=False)[source]

Select a cell measure construct by its identity.

New in version 3.0.0.

Parameters
identity: optional

Select the cell measure construct by:

• None. This is the default, which selects the cell

measure construct when there is only one of them.

• The identity or key of a cell measure construct.

• The identity or key of a domain axis construct that is spanned by a unique 1-d cell measure construct’s data.

• The position, in the field construct’s data, of a domain axis construct that is spanned by a unique 1-d cell measure construct’s data.

A construct identity is specified by a string (e.g. 'long_name=Cell Area', 'ncvar%areacello', etc.); a Query object (e.g. cf.eq('measure:area')); or a compiled regular expression (e.g. re.compile('^atmosphere')) that selects the relevant constructs whose identities match via re.search.

Each construct has a number of identities, and is selected if any of them match any of those provided. A construct’s identities are those returned by its identities method. In the following example, the construct x has six identities:

>>> x.identities()
['time',
'long_name=Time',
'foo=bar',
'standard_name=time',
'ncvar%t',
'T']


A construct key may optionally have the 'key%' prefix. For example 'cellmeasure2' and 'key%cellmeasure2' are both acceptable keys.

A position of a domain axis construct in the field construct’s data is specified by an integer index.

Note that in the output of a print call or dump method, a construct is always described by one of its identities, and so this description may always be used as an identity argument.

Parameter example:

identity='measure:area'

Parameter example:

identity='cell_area'

Parameter example:

identity='long_name=Cell Area'

Parameter example:

identity='cellmeasure1'

Parameter example:

identity='domainaxis2'

Parameter example:

identity=0

key: bool, optional

If True then return the selected construct key. By default the construct itself is returned.

default: optional

Return the value of the default parameter if a construct can not be found. If set to an Exception instance then it will be raised instead.

Returns
CellMeasureor str

The selected cell measure construct, or its key.

Examples:

TODO