TypeError：第一个参数必须是可调用的

Question

fs = codecs.open('grammar_new.txt', encoding='utf-8')
unidata=[]
d={}
fr=codecs.open('rule.txt', 'w')
for line in fs:
    line_data=line.split()
    for i in range(0,len(line_data)):
       unidata.append(line_data[i])


d = defaultdict(unidata)

while executing this code will generate error as d = defaultdict(unidata) TypeError: first argument must be callable..I want to store duplicate keys in dictionary

Answer 1

The first argument to defaultdict must be callable . You've passed an instance of list which isn't callable. You want to pass the 'list' type instead.

Typical use would be something like:

d = defaultdict(list)
for k, v in something:
    d[k].append(v)

Based on the unidata you seem to have provided in your comment, I think you want:

>>> from collections import defaultdict
>>> unidata = [[u'NP--->', u'N_NNP'], [u'NP--->', u'N_NN_S_NU'], [u'NP--->', u'N_NNP'], [u'NP--->', u'N_NNP'], [u'VGF--->', u'V_VM_VF'], [u'NP--->', u'N_NN']]
>>> d = defaultdict(list)
>>> for k, v in unidata:
...     d[k].append(v)
... 
>>> d
defaultdict(<type 'list'>, {u'VGF--->': [u'V_VM_VF'], u'NP--->': [u'N_NNP', u'N_NN_S_NU', u'N_NNP', u'N_NNP', u'N_NN']})

Answer 2

I want to store duplicate keys in dictionary

This is simply not possible. Keys in dictionaries are unique. I think what you want is this:

d = defaultdict(list)
with codecs.open('grammar_new.txt', encoding='utf-8') as f:
   for line in f:
      if len(line.rstrip()):
          key,value = line.rstrip().split()
          d[key].append(value)

print(d)

Now d will contain for each key a list that contains the corresponding values. Each key must be unique, but it can have any number of values, which can be duplicates.