string conversion

Question

Hi there, I’ve got a long string object which has been formatted like this

myString = “[name = john, family = candy, age = 72],[ name = jeff, family = Thomson, age = 24]”

of course the string is longer than this. Also i have 3 lists with related names:

Names    = []
Families = []
Ages     = []

I want to read that string character by character and take the data and append it into appropriate lists. Can anyone help me on this about how to separate the string into variables? The thing I need is something like this:

Names = [“john”, “jeff”, ...]
Families = [“candy”, “Thomson”, ...]
Ages = [72, 24, ...]

Answer 1

Break the problem down:

1. Parse the string into lists
2. Load the lists into your other lists.

You'll have a problem, because the entities between commas aren't nice dictionaries.

Answer 2

This can be most easily done using a regex. Basically, construct a regex that extracts the name,family and age from the string and extract the relevant data from the tuples returned to build your lists.

import re

if __name__=='__main__':
    myString = "[name = john adams, family = candy, age = 72],[ name = jeff, family = Thomson, age = 24]"
    answers=re.findall("\\[\\s*name = ([^,]+), family = (\\w+), age = (\\d+)\\]",myString)
    names=[x[0] for x in answers]
    families=[x[1] for x in answers]
    ages=map(int,(x[2] for x in answers))

    print "names: ",names
    print "families: ", families
    print "ages: ", ages 

Answer 3

import re

Names    = []
Families = []
Ages     = []
myString = "[name = john, family = candy, age = 72],[ name = jeff, family = Thomson, age = 24"

myregex = re.compile("name = (?P<name>.*?), family = (?P<family>.*?), age = (?P<age>.*)")

for list_ in myString.split(']'):
    found = re.search(myregex, list_).groupdict()
    Names.append(found['name'])
    Families.append(found['family'])
    Ages.append(int(found['age']))

Answer 4

You should parse that to a list of dictionaries, not three differente lists, co-related only by data order. Like in data = [ {"name": "John", "family": "Candy", "age": 72 }, ...]

One possibility, if you can't change the data source, is to do some naive parsing with string methods like split:

myString = "[name = john, family = candy, age = 72],[ name = jeff, family = Thomson, age = 24]"

data = []
for block in myString.split("]"):
    if not block: break
    block = block.split("[")[1]
    entry_dict = {}
    for part in block.split(","):
        key, value = part.split("=")
        key = key.strip()
        value = value.strip()
        if key == "age": value = int(value)
        entry_dict[key] = value
    data.append (entry_dict)

Or, if you are on python 2.7 (or 3.1) and want a shorter code, you can use a dict generator (you can use generators in other versions as well, just creating alist of tuples and adding a "dict" call) :

myString = "[name = john, family = candy, age = 72],[ name = jeff, family = Thomson, age = 24]"

data = []
for block in myString.split("]"):
    if not block: break
    block = block.split("[")[1]
    entry_dict = {}
    data.append ({(part.split("=")[0].strip(), part.split("=")[1].strip())  for part in block.split(",")  })

(in this version did not convert "age" to numbers, though)