CODEWITHSUNDEEP
pythonlist-comprehension
victorR
victorR

Reputation: 139

Return a list item from a null value using list comprehension

I'm using a list comprehension to get a list of numerical values that are separated by a semicolon, ;, within a string.

I need to get a 0 from missing values on either side of the semicolon.

Example string without missing values:

   job_from_serial_st = 'xxxxx\rxxxxxx\rxxxx\rGAX=77.00;85.00\rxxxxx\r'

Using my list comprehension I would get the following list of values: [7700, 8500]

But how can I get a list of values from strings like 'GAX=77.00;\r' or 'GAX=;85.00\r'?

I'm expecting to get the following lists from the example strings with missing values:

[7700, 0] or [0, 8500]

def get_term(A, B, phrase):   

    n = A.len()
    start = phrase.find(A) + n
    end = phrase.find(B, start)
    term = phrase[start:end]

    return term


# GET GAX NUMBER 
gax_nums = get_term(r'GAX=', r'\r\x1e\x1d', job_from_serial_st)
gax = [int(float(x) * 100) for x in gax_nums.split(';')]
print(gax)

Upvotes: 1

Views: 959

Answers (1)

benvc
benvc

Reputation: 15120

You can add a condition to the list comprehension to return 0 if there is no number before or after the semicolon (also replaced your function with a series of splits to retrieve the numbers from the string).

s = 'xxxxx\rxxxxxx\rxxxx\rGAX=77.00;\rxxxxx\r'
nums = s.split('GAX=')[1].split('\r')[0].split(';')

gax = [int(float(n) * 100) if n else 0 for n in nums]

print(gax)
# [7700, 0]

Upvotes: 1

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