Alternative for re.findall for python-CodePudding

I am using an arduino uno and a thermistor to measure the current temperature. I have been using re.findall to find the matching string in line 4, is there an alternative instead of using re.findall that has the same function? as I am not allowed to use re in my project. Thanks

def my_function(port):

    # Set COM Port.....
    ser = serial.Serial(port, 9600, timeout=0, 
    parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, rtscts=0)

my_function('COM3')

    # Set path to my Arduino device
    #portPath = my_function
baud = 9600
sample_time = 1 #Takes temperature every 1 second
sim_time = 1 #Graphs 5 data points

# Initializing Lists 
# Data Collection 
data_log = [] 
line_data = [] 

# Establishing Serial Connection 
connection = serial.Serial("com3",baud) 

# Calculating the length of data to collect based on the 
# sample time and simulation time (set by user) 
max_length = sim_time/sample_time 

# Collecting the data from the serial port 
    while True: 
        line = connection.readline()
        line_data = re.findall('\d*\.\d*',str(line))
        line_data = filter(None,line_data)
        line_data = [float(x) for x in line_data]
        line_data = [(x-32)*0.5556 for x in line_data] #list comprehension to convert line_data temp to celsius
        line_data = [ round(elem,2) for elem in line_data] #round temp to 2 dp
        if len(line_data) > 0:
            print("The current temperature is:"   str(line_data[0])   " celsius") 
            break

CodePudding user response：

Since no sample output is given, Here is a code that extracts all valid numbers from the text:

a = "Temperature = 54.3F 62.5, 79999 54.3°C 23.3C"

a =' '
temp = []
i = 0
while i < len(a):
    if (a[i].isdigit() or a[i] == '.'):
        if a[i] == '.' and '.' in temp[-1]:
            x = a.find(' ', i)
            i = x
            temp.pop()
        elif i == 0:
            temp[-1]  = a[i]
        elif len(temp)>0 and a[i-1] == temp[-1][-1]:
            temp[-1]  = a[i]
        else:
            temp.append(a[i])
    i  = 1
temp = list(map(float, temp)) # Float casting
print(temp)

Output:

['54.3', '62.5', '79999', '54.3', '23.3']

CodePudding user response：

Looking at this answer here: https://stackoverflow.com/a/4289557/7802476 A slight modification can also give decimals:

>>> txt = "h3110 23 cat 444.4 rabbit 11 2 dog"
>>> [float(s) for s in txt.split() if '.' in s and s.replace('.','').isdigit()]
>>> [444.4]

Your regex \d*\.\d* will match numbers such as {.2, 2., 2.2,...} but will not match {2} since \. has to be in the number. The above will also do the same.

EDIT: The solution won't handle numbers that are attached to a string {2.2°C} where as the regex does.

To make it handle units as well,

[float(s) for s in txt.split() if '.' in s and s.replace('.','').replace(f'{unit}', '').isdigit()]

Where unit can be '°C' or 'F' for temperature.

However, your regex matches all floating point numbers attached to any string. That is, cat2.2rabbit would also return 2.2, not sure if this should be returned.