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Added support for superscripts in variables and fixed bug with normal subscripted variables raised to powers

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Peter Baratta
2013-03-04 09:49:41 -07:00
parent 999ed17e6d
commit 66657db0be
1 changed files with 60 additions and 0 deletions
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60
lms/lib/symmath/formula.py
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@@ -247,6 +247,65 @@ class formula(object):
fix_hat(k)
fix_hat(xml)
def flatten_pmathml(xml):
'''
Give the text version of PMathML elements
'''
tag = gettag(xml)
if tag == 'mn': return xml.text
elif tag == 'mi': return xml.text
# elif tag == 'msub': return '_'.join([flatten_pmathml(y) for y in xml])
# elif tag == 'msup': return '^'.join([flatten_pmathml(y) for y in xml])
elif tag == 'mrow': return ''.join([flatten_pmathml(y) for y in xml])
raise Exception, '[flatten_pmathml] unknown tag %s' % tag
# find "tagged" superscripts
# they have the character \u200b in the superscript
# replace them with a__b so snuggle doesn't get confused
def fix_superscripts(xml):
for k in xml:
tag = gettag(k)
# match node to a superscript
if (tag == 'msup' and
len(k) == 2 and gettag(k[1]) == 'mrow' and
gettag(k[1][0]) == 'mo' and k[1][0].text == u'\u200b'): # whew
k[1].remove(k[1][0])
newk = etree.Element('mi')
newk.text = '%s__%s' % (flatten_pmathml(k[0]), flatten_pmathml(k[1]))
xml.replace(k, newk)
if (tag == 'msubsup' and
len(k) == 3 and gettag(k[2]) == 'mrow' and
gettag(k[2][0]) == 'mo' and k[2][0].text == u'\u200b'): # whew
k[2].remove(k[2][0])
newk = etree.Element('mi')
newk.text = '%s_%s__%s' % (flatten_pmathml(k[0]), flatten_pmathml(k[1]), flatten_pmathml(k[2]))
xml.replace(k, newk)
fix_superscripts(k)
fix_superscripts(xml)
# Snuggle returns an error when it sees an <msubsup>
# replace such elements with an <msup>, except the first element is of
# the form a_b. I.e. map a_b^c => (a_b)^c
def fix_msubsup(parent):
for child in parent:
# fix msubsup
if (gettag(child) == 'msubsup' and len(child) == 3):
newchild = etree.Element('msup')
newbase = etree.Element('mi')
newbase.text = '%s_%s' % (flatten_pmathml(child[0]), flatten_pmathml(child[1]))
newexp = child[2]
newchild.append(newbase)
newchild.append(newexp)
parent.replace(child, newchild)
fix_msubsup(child)
fix_msubsup(xml)
self.xml = xml
return self.xml
@@ -257,6 +316,7 @@ class formula(object):
try:
xml = self.preprocess_pmathml(self.expr)
except Exception, err:
# print 'Err %s while preprocessing; expr=%s' % (err, self.expr)
return "<html>Error! Cannot process pmathml</html>"
pmathml = etree.tostring(xml, pretty_print=True)
self.the_pmathml = pmathml