在python中将一个列表或列表列表进行字符串化并将其转换回原始形式的问题

Question

I have been trying to stringify a list and list of list and then convert it back to it's original form. Following are my 2 sample lists :

option_list = ['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1']
option_listoflist = [['1309', 'Blg 1', 500], ['1P09', 'Bdg 1', 4501], ['1226', 'Bdg 1', 600], ['1302', 'Bdg 1', 1432]]

I wrote this python code, based on some SO posts, where I am trying to stringify the above 2 lists and then try to convert them back but it is throwing error:

str1 = ''.join(option_list)
print(str1+'\n')
str_2_list = ast.literal_eval(str1)
print(str_2_list)

str2 = ''.join(option_listoflist)
print(str2+'\n')
str_2_listoflist = ast.literal_eval(str2)
print(str_2_listoflist)

When I execute this I get invalid syntax error at str_2_list = ast.literal_eval(str1) .

How can I stringify a list and list of list and then convert it back to it's original form?

NOTE: What I want to do is to convert ['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1'] to string version like this "['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1']" and then convert it back to original list. Similarly for a list of list

Answer 1

You are doing it wrong - conversion to string. Try str1 = str(options_list)

Answer 2

Since you seem to be trying to replicate JavaScript's JSON.stringify , just use the json module to do exactly that:

In [1]: import json

In [2]: option_list = ['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1']

In [3]: option_listoflist = [['1309', 'Blg 1', 500], ['1P09', 'Bdg 1', 4501], ['1226', 'Bdg 1', 600], ['1302', 'Bdg 1', 1432]]

In [4]: json.dumps(option_list)
Out[4]: '["1309", "1P09", "Bdg 1", "1226", "Bdg 1"]'

In [5]: json.dumps(option_listoflist)
Out[5]: '[["1309", "Blg 1", 500], ["1P09", "Bdg 1", 4501], ["1226", "Bdg 1", 600], ["1302", "Bdg 1", 1432]]'

In [6]: json.loads(json.dumps(option_list)) == option_list
Out[6]: True

In [7]: json.loads(json.dumps(option_listoflist)) == option_listoflist
Out[7]: True

Answer 3

Your ''.join(option_list) outputs '13091P09Bdg 11226Bdg 1' which can't be converted to list because the output string is not following list syntax.

Crrected Code

option_list = ['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1']
option_listoflist = [['1309', 'Blg 1', 500], ['1P09', 'Bdg 1', 4501], ['1226', 'Bdg 1', 600],['1302', 'Bdg 1', 1432]]
str1 = ','.join(option_list)
print(str1+'\n')
str_2_list = str1.split(',')
print(str_2_list)

str2 = ','.join(str(item) for innerlist in option_listoflist for item in innerlist)
print(str2+'\n')
str_2_listoflist=[str2.split(',')[i:i+3] for i in range(0, len(str2.split(',')), 3)]
for i in str_2_listoflist:
  i[2]=int(i[2])
print(str_2_listoflist)

Output:

1309,1P09,Bdg 1,1226,Bdg 1

['1309', '1P09', 'Bdg 1', '1226', 'Bdg 1']

1309,Blg 1,500,1P09,Bdg 1,4501,1226,Bdg 1,600,1302,Bdg 1,1432

[['1309', 'Blg 1', 500], ['1P09', 'Bdg 1', 4501], ['1226', 'Bdg 1', 600], ['1302', 'Bdg 1', 1432]]