SectionRef
child · exists · has_parent · has_trueparent · is_cas · nchild · parent · root · sec · trueparent

# SectionRef¶↑

Note

Much of this functionality is available in Python through Section methods in recent versions of NEURON. It is, however, sometimes necessary to use this class to interoperate with legacy code.

class SectionRef
Syntax:
sref = h.SectionRef(sec=section)
Description:

SectionRef keeps a pointer/reference to section. If the sec= argument is omitted, the reference is to the currently accessed section.

This class overcomes a HOC limitation where sections were not treated as objects.

SectionRef.sec
Syntax:
sref.sec
Description:

Returns the Section the SectionRef references.

from neuron import h

s = h.Section()
s2 = h.Section()
sref = h.SectionRef(sec=s2)

print (sref.sec==s)  # False
print (sref.sec==s2) # True


SectionRef.parent
Syntax:
sref.parent

Description:

Returns the parent of sref.sec.

Warning

If there is a chance that a section does not have a parent then SectionRef.has_parent() should be called first to avoid an execution error. Note that the parent is the current parent of sref.sec, not necessarily the parent when the SectionRef was created.

SectionRef.trueparent
Syntax:
sref.trueparent
Description:

Returns the trueparent of sref.sec.

This is normally identical to SectionRef.parent() except when the parent’s parent_connection() is equal to the parent’s section_orientation().

If there is a chance that a section does not have a trueparent then SectionRef.has_trueparent() should be called first to avoid an execution error.

SectionRef.child
Syntax:
sref.child[i]
Description:

Returns the ith child of sref.sec. Generally it is used in a context like

for child in sref.child:
print(child.hname())


Note that the children are the current children of sref.sec, not necessarily the same as when the SectionRef was created since sections may be deleted or re-connected subsequent to the instantiation of the SectionRef.

SectionRef.root
Syntax:
sref.root

Description:

Returns the root of sref.sec.

SectionRef.has_parent()
Syntax:
boolean = sref.has_parent()
Description:
Returns 1.0 if sref.sec has a parent and 0.0 if sref.sec is a root section. Invoking sref.parent when sref.sec is a root section will print an error message and halt execution.

SectionRef.has_trueparent()
Syntax:
boolean = sref.has_trueparent()
Description:
returns 1.0 if the sref.sec parent node is not the root node and 0.0 otherwise. Invoking sref.trueparent when it is the root node will print an error message and halt execution.

SectionRef.nchild()
Syntax:
num = sref.nchild()
Description:
Return the number of child sections connected to sref.sec as a float.

Note

To get the number of child sections as an int, use: num = len(sref.child)

SectionRef.is_cas()
Syntax:
boolean = sref.is_cas()
Description:
Returns 1.0 if this section reference is the currently accessed (default) section, 0.0 otherwise.

Note

An equivalent expression that evaluates to True or False is (sref.sec == h.cas()).

SectionRef.exists()
Syntax:
boolean = sref.exists()
Description:
Returns 1.0 if the referenced section has not been deleted, 0.0 otherwise.