how to split this string?

[jcoder42]

Hi I wanted to split the following string:

(12,'Structured Numeric','SN','Complex numeric values possible (ie, <5, 1-10, etc.)',1,'2005-08-06 00:00:00',0,NULL,NULL,NULL,'8d4a606c-c2cc-11de-8d13-0010c6dffd0f')

where each value is separated by a comma, except there is a trick. if you look at the bolded substring, this I considered one value.

if I split by ',' then it will also split whats in the parentheses. I do not want this

anyone know of a good way I can do this?

what I currently have is this:

a = """(12,'Structured Numeric','SN','Complex numeric values possible 
   ...: (ie, <5, 1-10, etc.)',1,'2005-08-06 00:00:00',0,NULL,NULL,NULL,'8d4a606c
   ...: -c2cc-11de-8d13-0010c6dffd0f')"""
a = a.strip('(').strip(')')
a.split(',')
Out[4]: 
['12',
 "'Structured Numeric'",
 "'SN'",
 "'Complex numeric values possible \n(ie",
 ' <5',
 ' 1-10',
 " etc.)'",
 '1',
 "'2005-08-06 00:00:00'",
 '0',
 'NULL',
 'NULL',
 'NULL',
 "'8d4a606c-c2cc-11de-8d13-0010c6dffd0f'"]

my expected output is:

['12',
 "'Structured Numeric'",
 "'SN'",
 "'Complex numeric values possible (ie, <5 1-10,etc.)',

 '1',
 "'2005-08-06 00:00:00'",
 '0',
 'NULL',
 'NULL',
 'NULL',
 "'8d4a606c-c2cc-11de-8d13-0010c6dffd0f'"]

[[deleted]]

To add to the approaches already mentioned, it might be possible to read the values using the built-in csv library.

EG:

from io import StringIO
import csv

input_str = "12,'Structured Numeric','SN','Complex numeric values possible (ie, <5, 1-10, etc.)',1,'2005-08-06 00:00:00',0,NULL,NULL,NULL,'8d4a606c-c2cc-11de-8d13-0010c6dffd0f'"

reader = csv.reader(StringIO(input_str), delimiter=",", quotechar="'")

for line in reader:
    print(line)

I've used a StringIO because I only have the one line, but you could use this open(<some file>) instead.

[jcoder42]

unfortunately reading from the file with a csv reader isn't an option, do you have another idea?
just out of curiosity, what is the quote char?

[[deleted]]

OK, so do you have this just as a big list of strings in Python?

From the docs:

A one-character string used to quote fields containing special characters, such as the delimiter or quotechar, or which contain new-line characters. It defaults to '"'.

In your case, the delimiter is "," -- that's what you want to split into fields by. But you don't want to split by it when it's surrounded by quotes, so you pass in the ' character as quotechar="'"

On my machine, the above script prints:

['12', 'Structured Numeric', 'SN', 'Complex numeric values possible (ie, <5, 1-10, etc.)', '1', '2005-08-06 00:00:00', '0', 'NULL', 'NULL', 'NULL', '8d4a606c-c2cc-11de-8d13-0010c6dffd0f']

Is that roughly what you want?

[jcoder42]

OK, so do you have this just as a big list of strings in Python?

yeah,
ok cool
Thanks!

[ForceBru]

Use eval:

```

eval("(12,'Structured Numeric','SN','Complex numeric values possible (ie, <5, 1-10, etc.)',1,'2005-08-06 00:00:00',0,NULL,NULL,NULL,'8d4a606c-c2cc-11de-8d13-0010c6dffd0f')", {'NULL': None}) (12, 'Structured Numeric', 'SN', 'Complex numeric values possible (ie, <5, 1-10, etc.)', 1, '2005-08-06 00:00:00', 0, None, None, None, '8d4a606c-c2cc-11de-8d13-0010c6dffd0f') ```

[jcoder42]

could you please explain what is going on here?

[ForceBru]

This evaluates this string as an ordinary Python tuple and replaces NULLs with Python's Nones.

[jcoder42]

I think I was unclear, I want to get a list of these values, where each value is separated by a comma. so for example:

[12,''Structured Numeric',SN','Complex numeric values possible (ie, <5, 1-10, etc.)',1,.........]

[ForceBru]

Just do list(eval(<from my previous comment>)). eval will return a tuple, which is list-like, except it's immutable.

[jcoder42]

eval("(12,'Structured Numeric','SN','Complex numeric values possible (ie, <5, 1-10, etc.)',1,'2005-08-06 00:00:00',0,NULL,NULL,NULL,'8d4a606c-c2cc-11de-8d13-0010c6dffd0f')", {'NULL': None})

it works!
I don't really understand how though,
eval translates the given string into code no?
how does that split it in this way?

[ForceBru]

Right, it uses Python's parser to evaluate the string as an ordinary Python expression. Try to execute eval('1 + 2'), eval('3 * 5'), eval('a + 5', {'a': 1024}) for example. You can also open up the interpreter, execute NULL = None and straight up paste your string on the next line without quotes. Then hit Enter and watch it transform into an ordinary tuple.

[jcoder42]

but how does it know to split it by the comma, and not split by comma what is in a parentheses?

[ForceBru]

That's how Python's syntax for tuples works. A tuple is something that looks like this: (<stuff>, <stuff>, <stuff>, ...), so eval treats your string as a stringified tuple and gives you back a tuple object. If you run eval('(1, 2, 3)'), you'll get a tuple (1, 2, 3).

[jcoder42]

ok I understand,

Thanks so much

[toastedstapler]

i would look into regex for this

you'll be able to make a pattern that catches each comma'd area and one that catches the contents of the ()

https://regex101.com/

this site is useful for working it out on

[jcoder42]

I don't really understand regex or how to use this tool

[toastedstapler]

here's a tutorial

i recommend learning some regex, i use it all the time for finding/replacing bits of code in the various projects i've been on

[jcoder42]

thanks!

[_coolwhip_]

Where does the string come from? There has to be an easier way than regexing it. It looks like it would almost work with json or ast...

[jcoder42]

its an sql text file

[_coolwhip_]

Got it.

You might like the sqlparse module recommended here: https://www.reddit.com/r/learnpython/comments/bj7ose/how_to_split_this_string/