Python literal_eval - convert stringed list into python list

 Python ast.literal_eval() 

Is a very useful method which can evaluate a string contents for python datatypes . If the string happens to have valid datatype inside the string it will initialised . One use case in which I personally used it was to convert strings values stored csv files . The rows contained "list" as string and wanted to run operations on it. These must be converted into list format first ; ast.literal_eval()  achieves that !

#python code 
import ast 

#string containing a list
stringed_list= "[1,2,3]"

#converting stringed list into python list
converted_list = ast.ast.literal_eval(string_list) 

print(type(stringed_list)) # 'str'

print(type(converted_list)) # 'list'

Even though this is a really convenient way to convert stringed list back into python list ,  it is slow. This works great for moderately small csv data files in which we can store scaled parameter lists , etc as string . 

When size of the file increases so does the processing time and it is very noticeable. So if your csv files contains few million rows of values or more , it is better to store the data by python pickling.

Python pickling is considerably faster at least 3 to 5 times than running "literal_eval".