def __init__(self, source, index):
self._source = simplify(source)
self._start, self._stop = get_slice_indices(len(source), index)
self._len = self._stop - self._start
if self._len <= 0:
self.replacement = Constant()
self._len = 0
elif self._start <= 0 and self._stop >= len(source):
self.replacement = source
else:
source.replacement_available.connect(self._replace_source)
self._replace_source()
def replace(self, index, replacement):
"""Replace the given element (or slice) with a value
(This is the equivalent of :token:`__setitem__`, but it returns a new
Expression instead of modifying the old.)
:param index: Index, or slice, to be replaced
:param replacement: The new value
:type replacement: Expression, tuple, or a simple number
Any element of an expression can be replaced::
>>> Constant(1, 2, 3).replace(0, -2)
<-2.0, 2.0, 3.0>
This can be used to change the size of the expression::
>>> Constant(1, 2, 3).replace(0, (-2, -3))
<-2.0, -3.0, 2.0, 3.0>
Slices can be replaced as well::
>>> Constant(1, 2, 3).replace(slice(0, -1), (-2, -3))
<-2.0, -3.0, 3.0>
>>> Constant(1, 2, 3).replace(slice(1, 1), (-8, -9))
<1.0, -8.0, -9.0, 2.0, 3.0>
>>> Constant(1, 2, 3).replace(slice(1, None), ())
<1.0>
>>> Constant(1, 2, 3).replace(slice(None, None), ())
<>
When replacing a slice by a plain number, the number is repeated
so that the size does not change::
>>> Constant(1, 2, 3).replace(slice(0, -1), -1)
<-1.0, -1.0, 3.0>
Of course this does not happen when using a tuple or expression::
>>> Constant(1, 2, 3).replace(slice(0, -1), (-1,))
<-1.0, 3.0>
>>> Constant(1, 2, 3).replace(slice(0, -1), Constant(-1))
<-1.0, 3.0>
"""
start, stop = get_slice_indices(len(self), index)
replacement = coerce(replacement, size=stop - start, strict=False)
return simplify(Concat(self[:start], replacement, self[stop:]))
def __getitem__(self, index):
start, end = get_slice_indices(len(self), index)
new_children = []
for child in self._children:
child_len = len(child)
if end <= 0:
break
elif start >= child_len:
pass
else:
if start <= 0 and end >= child_len:
new_children.append(child)
else:
new_children.append(child[start:end])
start -= child_len
if start < 0:
start = 0
end -= child_len
return Concat(*new_children)
def __getitem__(self, index):
start, end = get_slice_indices(len(self), index)
index = slice(self._start + start, self._start + end)
return _ComponentProperty(
vector_property=self._vector_property,
index=index)
def __init__(self, vector_property, index):
self._vector_property = vector_property
self._start, self._end = get_slice_indices(len(vector_property), index)
self.name = vector_property._get_component_name(self._start, self._end)
def __getitem__(self, index):
start, end = get_slice_indices(len(self), index)
return Constant(*self._value[slice(start, end)])
