StringFunctions
alias · alias_list · head · is_artificial · is_name · is_point_process · left · len · references · right · substr · tail

StringFunctions (String Manipulation Class)

class StringFunctions
Syntax:
obj = h.StringFunctions()
Description:
The StringFunctions class contains functions which you can apply to a strdef. This class exists purely for the utility of preventing pollution of name space with string operations.

Example:

from neuron import h
sf = h.StringFunctions()
StringFunctions.len()
Syntax:
length = strobj.len(str)
Description:
Return the length of a string.
Example:
from neuron import h
s = h.ref("hello")
sf = h.StringFunctions()
length = sf.len(s)
print(length)
StringFunctions.substr()
Syntax:
index = strobj.substr(s1, s2)
Description:
Return the index into s1 of the first occurrence of s2. If s2 isn’t a substring then the return value is -1.
Example:
from neuron import h
s1 = h.ref("allowed")
s2 = h.ref("low")
sf = h.StringFunctions()
index = sf.substr(s1, s2)
StringFunctions.head()
Syntax:
strobj.head(str, "regexp", result)
Description:
The result contains the head of the string up to but not including the regexp. returns index of last char.
Example:
from neuron import h
s1 = h.ref("hello world")
s2 = h.ref("")
sf = h.StringFunctions()
index = sf.head(s1, "[e]", s2)
print(s2[0])
StringFunctions.tail()
Syntax:
strobj.tail(str, "regexp", result)
Description:

The result contains the tail of the string from the char following regexp to the end of the string. return index of first char.

Other functions can be added as needed, eg., index(s1, c1), char(s1, i), etc. without polluting the global name space. In recent versions functions can return strings.

Example:
from neuron import h
s1 = h.ref("hello world")
s2 = h.ref("")
sf = h.StringFunctions()
index = sf.tail(s1, "[e]", s2)
print(s2[0])
StringFunctions.right()
Syntax:
strobj.right(str, n)
Description:
Removes first n characters from str and puts the result in str.
Example:
from neuron import h
s = h.ref("hello")
sf = h.StringFunctions()
sf.right(s, 3)
print(s[0])
StringFunctions.left()
Syntax:
.left(str, n)
Description:
Removes all but first n characters from str and puts the result in str
Example:
from neuron import h
s = h.ref("hello")
sf = h.StringFunctions()
sf.left(s, 3)
print(s[0])
StringFunctions.is_name()
Syntax:
.is_name(item)
Description:
Returns True if the item is the name of a symbol, False otherwise. This is so useful that the same thing is available with the top level name_declared() function (except that returns 1 or 0 instead of True or False).
Example:
from neuron import h
s1 = h.ref("hello world")
sf = h.StringFunctions()
name = sf.is_name(s1)
print(name)

Here is an example with one string that works, and another that does not:

from neuron import h
sf = h.StringFunctions()
# valid name
print(sf.is_name("xvalue"))
# invalid name
print(sf.is_name("xsquiggle"))

Note

This is approximately equivalent to item in dir(h).

StringFunctions.alias()
Syntax:

.alias(obj, "name", &var2)

.alias(obj, "name", obj2)

.alias(obj, "name")

.alias(obj)

Description:
“name” becomes a public variable for obj and points to the scalar var2 or object obj2. obj.name may be used anywhere the var2 or obj2 may be used. With no third arg, the “name” is removed from the objects alias list. With no second arg, the objects alias list is cleared.
Example:
from neuron import h
sf = h.StringFunctions()
v = h.Vector()
sf.alias(v, 't', h._ref_t)
print('v.t = %g' % v.t)
h.t = 42
print('v.t = %g' % v.t)
StringFunctions.alias_list()
Syntax:
list = sf.alias_list(obj)
Description:
Return a new List object containing String objects which contain the alias names.

Warning

The String class is not a built-in class. It generally gets declared when the nrngui.hoc file is loaded and lives in stdlib.hoc. Note that the String class must exist and its constructor must allow a single strdef argument. Minimally:

Example:
from neuron import h
h.load_file('stdrun.hoc')
sf = h.StringFunctions()
v = h.Vector()
al = sf.alias_list(v)
print(al)
StringFunctions.references()
Syntax:
sf.references(object)
Description:
Prints the number of references to the object and all objref names that reference that object (including references via HBox, VBox, and List). It also prints the number of references found.
Example:
from neuron import h
s1 = h.Section(name='soma')
strobj = h.StringFunctions()
strobj.references(s1)
StringFunctions.is_point_process()
Syntax:
i = sf.is_point_process(object)
Description:
Returns 0 if the object is not a POINT_PROCESS. Otherwise returns the point type (which is always 1 greater than the index into the MechanismType(1) list).
Example:
from neuron import h
h.load_file('stdrun.hoc')
s1 = h.Section(name='soma')
syn = h.ExpSyn(s1(0.5))
sf = h.StringFunctions()
# not point process
print(sf.is_point_process(s1))
# point process
print(sf.is_point_process(syn))
c = h.IntFire1()
# point process
print(ssf.is_point_process(c))
StringFunctions.is_artificial()
Syntax:
i = sf.is_artificial(object)
Description:
Returns 0 if the object is not an ARTIFICIAL_CELL. Otherwise returns the point type (which is always 1 greater than the index into the MechanismType(1) list).
Example:
from neuron import h
h.load_file('stdrun.hoc')
s1 = h.Section(name='soma')
syn = h.ExpSyn(s1(0.5))
# initiate string function
sf = h.StringFunctions()
c = h.IntFire1()
# artificial
print(sf.is_artificial(c))
# not artificial
print(sf.is_artificial(syn))