Where is this white space coming from?

I am post-processing output from a python script that generates GCODE for my homebrew pen plotter.

The post-processor adds a white space in my GCODE right after a crucial bit of information (after every X and Y coordinate value), causing the GCODE to become invalid.

Example of how it should look:

Example of how my output looks:

I have tried to remove the \s operators from the suspected pieces of code, I have tried using .lstrip() in various areas to remove the white spaces but to no avail. I have also removed all double spaces that were present in the code, and nothing has helped so far.

I suspect this code is doing it:

def round_coordinates(self,parameters) :
    try: 
        round_ = int(parameters)
    except :    
        self.error("Bad parameters for round. Round should be an integer! \n(Parameters: '%s')"%(parameters), "error")      
    gcode = ""
    for s in self.gcode.split("\n"):
        for a in "xyzijkaf" :
            r = re.search(r"(?i)("+a+r")\s*(-?\s*(\d*\.?\d*))", s)
            if r : 

                if r.group(2)!="":
                    s = re.sub(
                                r"(?i)("+a+r")\s*(-?)\s*(\d*\.?\d*)",
                                (r"\1 %0."+str(round_)+"f" if round_>0 else r"\1 %d")%round(float(r.group(2)),round_),
                                s)
        gcode += s + "\n"
    self.gcode = gcode

I am hoping to be able to find out where the whitespace comes from, I may not showing the right bit of code so I have linked the source file. It appears at line 2648 and at line 5440 there is also a round function present that seems to be related.

Here is a pastebin to the complete code: https://pastebin.com/s8J1H8r6

I have attached an example which can be run to check this. I find this interesting but I was not able to find a way to solve it in a nice way... I will update this with better answer if I come across it.

For now, I see that we need to put some character between \1 and %d for the code to work. I would NOT use following to solve the issue, but it works at least. What I did was to put --- between the two, and then later remove it using replace function.

import re
def round_coordinates() :
    round_ = 5 

    gcode = """O1000
T1 M6
G0 G90 G40 G21 G17 G94 G80
G54 X-75 Y-25 S500 M3  
G43 Z100 H1
Z5
G1 Z-20 F100
X-50 M8            
Y0                 
X0 Y50               
X50 Y0             
X0 Y-50           
X-50 Y0      
Y25          
X-75  
G0 Z100
M30"""

    for s in gcode.split("\n"):
        for a in "xyzijkaf" :
            r = re.search(r"(?i)("+a+r")\s*(-?\s*(\d*\.?\d*))", s)
            if r : 

                if r.group(2)!="":
                    s = re.sub(
                                r"(?i)("+a+r")\s*(-?)\s*(\d*\.?\d*)",
                                (r"\1---%0."+str(round_)+"f" if round_>0 else r"\1---%d")%round(float(r.group(2)),round_),
                                s)
                    s = s.replace("---", "")
        gcode += s + "\n"
    return gcode

print(round_coordinates())

PS. I would use format function instead of % I guess...