python: parse a colon-separated formatted string

Question

I need to write a python script (I'm a newbie in python but would like to take this a practice) to parse a message of the following format:

T:L:x1:x2:x3:...T1:L1:y1:y2:y3...Tn:Ln:z1:z2:z3:...

where T holds a type, L is the length and x1..xn is the actual data of the type T1-Tn. Each character is separated with : symbol, all values always come in HEX representation.

For example:

1:4:a:5:6:7:2:10:72:75:63:6f:6e:74:72:6f:6c:6c:65:72:2e:6f:72:67

(Type1=1, Length1=4, Type2=2, Length2=16 (10 in hex))

The parsed messages should be stored in dictionary (I think this is the most appropriate data structure, but I'd be glad to hear some other suggestions).

So I am probably going to split the text, extract type and length, walk further and extract L bytes and store them in a dict with T as a key.

So I will run a loop, how do I determine the end of string, so that I can break out of the loop?
The actual data (x1-x3... for example) has to be stored in dictionary with : removed. I'm not sure how to do that.

I'd appreciate to learn about more efficient approach of parsing the string. Thanks!

please put an example of exact syntax you would like to parse, not a template — anon01
– anon01, Commented Oct 23, 2021 at 21:09
If you control the data source, I would highly recommend changing the format. This will be error prone — anon01
– anon01, Commented Oct 23, 2021 at 21:59
How I haven't thought about it before... I updated my answer. Can you check it, please? — Corralien
– Corralien, Commented Oct 24, 2021 at 6:39

anon01 · Accepted Answer · 2021-10-23 22:09:31Z

2

Something like this should work:

ss = "1:4:a:5:6:7:2:10:72:75:63:6f:6e:74:72:6f:6c:6c:65:72:2e:6f:72:67".split(":")

d = {}
idx = 0
while idx < len(ss):
    key = ss[idx]
    idx += 1
    length = int(ss[idx])
    idx += 1
    arr = ss[idx:idx+length]
    d[key] = arr
    idx += length

output d:

{'1': ['a', '5', '6', '7'],
 '2': ['72', '75', '63', '6f', '6e', '74', '72', '6f', '6c', '6c'],
 '65': ['2e', '6f', '72', '67']}

answered Oct 23, 2021 at 22:09

anon01

11.2k8 gold badges41 silver badges64 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Corralien Over a year ago

I don't think this is the expect outcome.

anon01 Over a year ago

@Corralien this follows the parsing rules type:length:<values> as outlined in the question. It looks like there may be a typo in the sample data

Corralien · Accepted Answer · 2021-10-24 06:38:52Z

1

Create an iterator over your string:

message = '1:4:a:5:6:7:2:10:72:75:63:6f:6e:74:72:6f:6c:6c:65:72:2e:6f:72:67'

code = iter(message.split(':'))
data = {}

for t in code:
    l = int(next(code), 16)
    d = [next(code) for _ in range(l)]
    data[t] = d

Output:

>>> data
{'1': ['a', '5', '6', '7'],
 '2': ['72', '75', '63', '6f', '6e', '74', '72', '6f', '6c', '6c', '65', '72', '2e', '6f', '72', '67']}

edited Oct 24, 2021 at 6:38

answered Oct 23, 2021 at 22:11

Corralien

121k8 gold badges44 silver badges69 bronze badges

Collectives™ on Stack Overflow

python: parse a colon-separated formatted string

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related