我有以下递归代码,在每个节点我调用sql查询来获取节点属于父节点。Python:超过最大递归深度
这里是错误:
def returnCategoryQuery(query, variables={}):
cursor = db.cursor(cursors.DictCursor);
catResults = [];
try:
cursor.execute(query, variables);
for categoryRow in cursor.fetchall():
catResults.append(categoryRow['cl_to']);
return catResults;
except Exception, e:
traceback.print_exc();
我居然没有上述方法的任何问题,但我把它给反正:
,我打电话让SQL结果Exception RuntimeError: 'maximum recursion depth exceeded' in <bound method DictCursor.__del__ of <MySQLdb.cursors.DictCursor object at 0x879768c>> ignored
RuntimeError: maximum recursion depth exceeded while calling a Python object
Exception AttributeError: "'DictCursor' object has no attribute 'connection'" in <bound method DictCursor.__del__ of <MySQLdb.cursors.DictCursor object at 0x879776c>> ignored
方法给出适当的问题概述。
递归代码:
def leaves(first, path=[]):
if first:
for elem in first:
if elem.lower() != 'someString'.lower():
if elem not in path:
queryVariable = {'title': elem}
for sublist in leaves(returnCategoryQuery(categoryQuery, variables=queryVariable)):
path.append(sublist)
yield sublist
yield elem
调用递归函数
for key, value in idTitleDictionary.iteritems():
for startCategory in value[0]:
print startCategory + " ==== Start Category";
categoryResults = [];
try:
categoryRow = "";
baseCategoryTree[startCategory] = [];
#print categoryQuery % {'title': startCategory};
cursor.execute(categoryQuery, {'title': startCategory});
done = False;
while not done:
categoryRow = cursor.fetchone();
if not categoryRow:
done = True;
continue;
rowValue = categoryRow['cl_to'];
categoryResults.append(rowValue);
except Exception, e:
traceback.print_exc();
try:
print "Printing depth " + str(depth);
baseCategoryTree[startCategory].append(leaves(categoryResults))
except Exception, e:
traceback.print_exc();
代码打印的字典,
print "---Printing-------"
for key, value in baseCategoryTree.iteritems():
print key,
for elem in value[0]:
print elem + ',';
raw_input("Press Enter to continue...")
print
如果递归太深,我应该得到的错误当我调用递归函数时,但是当我打印字典时出现此错误。
迭代而不是递归地重写它。 –
'首先:'检查对于elem来说是多余的:'。如果查询返回一个空的结果列表,那么迭代它将简单地,正确地做任何事情,如你所愿。此外,你可以创建列表更简单的清单理解(和那些分号是不必要的,通常被认为是丑陋:)) –
@KarlKnechtel对不起,关于分号,你能告诉我只是进入Python编程.... :) –