我怎么能解决python中的内存错误

Question

################################################################################
#...................Program to create  feature vector (N-grams) ...............
################################################################################
import ast
import csv
import os
import sys

from string import *
from BST import Node
import ast

maxInt = sys.maxsize
decrement = True
while decrement:
    # decrease the maxInt value by factor 10 
    # as long as the OverflowError occurs.
    decrement = False
    try:
        csv.field_size_limit(maxInt)
    except OverflowError:
        maxInt = int(maxInt/10)
        decrement = True

def File_Write(filename,write_ist):
    filewrite=open(filename,"w")
    filewrite.writerows(str(write_ist))
    filewrite.close()

#################################################################################
#................Function to read the files and create the FVT...................
# Change 2,3,4,5,6,7     
#################################################################################

def read_file_list(bigram,class_label) :      
        frqlist=[]
        root.reset_frequency()
        for i in range (0,len(bigram)):                       
                        row=str(bigram[i])

                        row = row.strip()
                        row = row.replace('(','')
                        row = row.replace(')','')
                        row = row.replace("'",'')
                        row = row.replace(",",' ')
                        node, parent = root.lookup(row)
                        if node :

                                root.increment_frequency(node)
        frqlist = root.print_tree()
        ##              Attach the class_label............

        root.finalize_frq_lst(class_label )
        root.write_to_csv(file_write1)



##################################################################################
#.................................MAIN PROGRAM....................................
##################################################################################
feature_list = ""
root_flag = 'false'


file_path_data = "/home/xxx/Project/Dataset/Cross/N_grams/7_POStags.csv"        ;##Input file containing Bigrams of blogdata
fp_data=csv.reader(open(file_path_data,"r"),delimiter=',')

file_path_feature = "/home/xxx/Project/Dataset/Cross/N_gram_Features/7_gram.txt"     ;##Input file containing sorted Bigrams 
fp_feature=open(file_path_feature,"r")
list1=fp_feature.read()
#### Convert String into list ...................
read_list=ast.literal_eval(list1)
read_list1=list(set(read_list))
print read_list1
for i in range(0,len(read_list)):
            feature=str(read_list[i])
            feature = feature.strip()
            feature = feature.replace('(','')
            feature = feature.replace(')','')
            feature = feature.replace("'",'')
            feature = feature.replace(",",' ')
            if root_flag == 'false':
                    root = Node( feature )
                    root_flag = 'true'                        
            else :
                    root.insert(feature)

            feature_list = feature_list + "\n" + feature
feature_list1 = feature_list.strip()
line = feature_list1.split('\n')
##print "#######################################################################"     
##print line
line1 = list(set(line))
print len(line1)
##print "#######################################################################"
line1.sort()
i=1



######Setting the path for input and output files .......................
output_file = "/home/xxx/Project/Dataset/Cross/N_grams_recored/7_gram.csv"          ;##Output file..............
with open(output_file,'w') as fo :
    file_write1 = csv.writer(fo, delimiter=',', quotechar='"')
    file_write1.writerow(line1)
    #### Write header data into output file      
    for data in fp_data :
        feature=ast.literal_eval(data[0])
        class_label=data[1]
        read_file_list(feature,class_label)
        print feature
        print i
        i=i+1

这是我在3277样本数据中记录7克计数的代码。我正在尝试创建76克7克的BST。但是我得到这样的错误

Traceback (most recent call last):
  File "N_gram_Record (2-7).py", line 79, in <module>
    read_list=ast.literal_eval(list1)
  File "/usr/lib/python2.7/ast.py", line 49, in literal_eval
    node_or_string = parse(node_or_string, mode='eval')
  File "/usr/lib/python2.7/ast.py", line 37, in parse
    return compile(source, filename, mode, PyCF_ONLY_AST)
MemoryError

我认为记忆错误是在我试图创造7克的bst以来，因为其数量为76000.所以任何想法都要克服这个问题???