How does the following codes do

[lilzz]

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for x in range(1, self.max_x):
            for y in range(1, self.max_y):
                if x in (3, 10):
                    if y % 2 == 1:
                        self.b_tiles[(x, y)] = ["0" * 42 for i in range(16)]
                    else:
                        self.t_tiles[(x, y)] = ["0" * 42 for i in range(16)]
                else:
                    self.l_tiles[(x, y)] = ["0" * 54 for i in range(16)]

1)What's "0"*42 for i in range(16)?

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 match = re.match(r"input(\d)_(\d)", netname)

2)Why need to have 2 (\d)?

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 netname="ram/ADDR_%d" % (idx1*4 + idx2)

3)What's the 2 nd purpose of %?

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import re, sys
match = re.match(r"ram/DATA_(\d+)", netname)

4)what's the difference between (\d+) and (\d)?
5)What's re.match?

[ghp]

Hello,
many questions.
(1) "0"*42 just builds a string of 42 zeroes. And the trailing for statement builds 16 elements of this. Note the [] brackets around this. When I find expressions like this, I pack them in a print statement and execute.

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print ( ["0" * 4 for i in range(3)] )
['0000', '0000', '0000']

I reduced the number of repeats to make it a little bit shorter.

(5) re is a package in python which handles 'regular expressions'. It provides some functions like re.match() or re.find(). The re.match() is a very powerful string function, which allows to find out whether a certain string matches a pattern. See https://docs.python.org/2/library/re.html for some explanation. It uses the r"something" as a first parameter, which describes the pattern, and a second string which is checked whether it matches the pattern or not.

(4) patterns describe the data you want to check. The '\d' is for "one digit". But sometimes there are multiple digits needed. The '+'-sign after a char, escape sequence or group says 'match at least one or more'. As the brackets () also are special characters in this syntax, the pattern r"ram/DATA_(\d+)" would match "ram/DATA_1", "ram/DATA_000" and all other combinations like this. But not "ram/DATA_ABC" (and of course not "cookie").

(2) With answer(4), you will see that r"input(\d)_(\d)" matches something like "input2_4".

(3) the Percent sign between Strings is a 'insert the following data into the formatting definitions of the string left". In first String is a %d, and at runtime the code formats the value of (idx1*4 + idx2) as a decimal.

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print ( "ram/ADDR_%d" % 23 )
ram/ADDR_23

Regards,
Gerhard