def ichistogram_int(prob, values, qumul):
"""
Calculates the inverse value of an input CUMULATIVE histogram.
'values' is a list/tuple with INTEGERS in ascending order - A MUST!
These values represent bin end points and must be one more than
the number of cumulative frequencies, and where...
...'qumul' are the corresponding CUMULATIVE FREQUENCIES such that
qumul[k] = P(x<=values[k+1]).
NB The first element of the values list is will never be returned!
The first integer to be returned is values[0] + 1 !!!!
The cumulative frequencies must of course obey qumul[k+1] >= qumul[k],
otherwise an exception will be raised!
The values of the integer random variate are assumed to be uniformly
distributed within each bin.
"""
nvalues = len(values)
nqumul = len(qumul)
# Input check ---
_assertprob(prob, 'ichistogram_int')
errtxt1 = "Lengths of input lists are incompatible in ichistogram_int!"
assert nqumul == nvalues-1, errtxt1
assert qumul[-1] == 1.0
assert 0.0 <= qumul[0] and qumul[0] <= 1.0
# ---
errtxt2 = "qumul list is not in order in ichistogram_int!"
for k in range(1, nqumul):
assert qumul[k] >= qumul[k-1], errtxt2
pass
# ---
errtxt3 = "all values in values list must be integers in ichistogram_int!"
errtxt4 = "values list is not in order in ichistogram_int!"
assert is_integer(values[0]), errtxt3
for k in range(1, nvalues):
assert is_integer(values[k]), errtxt3
assert values[k] >= values[k-1], errtxt4
pass
# ---
# The routine itself.................
pcopy = list(qumul)
pcopy.insert(0, 0.0)
k = bisect(pcopy, prob) # bisect used instead of binSearch
pdiff = prob - pcopy[k-1]
pinter = pcopy[k] - pcopy[k-1]
vinter = values[k] - values[k-1]
x = values[k-1] + vinter*pdiff/float(pinter)
x = int(x+1.0)
return x
def splice(self, offset, length, x):
"""
Analogous to Perl's splice (but all arguments must be present and x
must be a single number/string or a list/stack)
This is how it works: remove the slice self(offset:offset+length)
and replace it with the contents of x.
If offset < 0 then the offset is from the bottom of the present
object and upward - offset will then be len(self) - abs(offset).
If length < 0, then length = len(self) - 1 will be used.
offset > len(self) or offset+length > len(self) is OK.
Returns the slice removed as a stack (or None if nothing was removed).
"""
assert is_integer(offset), "offset must be an integer in splice!"
assert is_integer(length), "length must be an integer in splice!"
if offset < 0: index1 = len(self) + offset
else: index1 = offset
errtxt = "Negative offset must not try to reach below the "
errtxt += "bottom element of the object stack in splice!"
assert index1 >= 0, errtxt
if length < 0: index2 = len(self) - 1
else: index2 = index1 + length
try:
removed = Stack(self[index1:index2])
del self[index1:index2]
except IndexError:
removed = None
if len(removed) == 0: removed = None
if not isinstance(x, list): x = [x]
for element in x:
self.insert(index1, element)
index1 += 1
return removed # A stack (or None)
def splice(self, offset, length, x):
"""
Analogous to Perl's splice (but all arguments must be present and x
must be a single number/string or a list/stack)
This is how it works: remove the slice self(offset:offset+length)
and replace it with the contents of x.
If offset < 0 then the offset is from the bottom of the present
object and upward - offset will then be len(self) - abs(offset).
If length < 0, then length = len(self) - 1 will be used.
offset > len(self) or offset+length > len(self) is OK.
Returns the slice removed as a stack (or None if nothing was removed).
"""
assert is_integer(offset), "offset must be an integer in splice!"
assert is_integer(length), "length must be an integer in splice!"
if offset < 0: index1 = len(self) + offset
else: index1 = offset
errtxt = "Negative offset must not try to reach below the "
errtxt += "bottom element of the object stack in splice!"
assert index1 >= 0, errtxt
if length < 0: index2 = len(self) - 1
else: index2 = index1 + length
try:
removed = Stack(self[index1:index2])
del self[index1:index2]
except IndexError:
removed = None
if len(removed) == 0: removed = None
if not isinstance(x, list): x = [x]
for element in x:
self.insert(index1, element)
index1 += 1
return removed # A stack (or None)
