Question 22094 in Mysql Question posted in
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How to convert a three digit integer (xxx) with a 1 decimal place float (xx.x)? – Mysql

Currently I’m getting data from some sensors with voltage(V) and current(C) values which is decoded into text as V040038038039C125067 to be stored in MYSQL DB table. The voltage contains 4 different voltage values combined while the current contains 2 different current values combined where each value represented by 3 digits in the format of Voltage xx.x C: Current xx.x. For example, the current value of C125067 is actually 12.5 and 06.7A respectively. I tried to use python slicing some and some simple math to achieve this by dividing the values by 10 e.g. C125067 = 125/10 = 12.5. While this works for integers with first non-zero values (e.g. 125), when I tried to perform the same for values such as 040 or 067, I get the SyntaxError: leading zeros in decimal integer literals are not permitted error. Are there any better ways to achieve the desired decoding output of xx.x or to insert a decimal point before the last digit etc? Thanks.

v1 = voltage[1:4]
v2 = voltage[4:7]
v3 = voltage[7:10]
v4 = voltage[10:13]
c1 = current[1:4]
c2 = current[4:7]

volt_1 = int(v1)/10
volt_2 = int(v2)/10
volt_3 = int(v3)/10
volt_4 = int(v4)/10

curr_1 = int(c1)/10
curr_2 = int(c2)/10
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3

Answers


  1. 0

    This is a Very Simple Problem
    What you have to do is just divide the number by 10 and convert it into float with float inbuilt function in python.

    a = int(input("Enter a random number: "))
print(float(a/10))

    now apply it in your problem.

    volt_1 = float(int(v1)/10)
volt_2 = float(int(v2)/10)
volt_3 = float(int(v3)/10)
volt_4 = float(int(v4)/10)

curr_1 = float(int(c1)/10)
curr_2 = float(int(c2)/10)
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  2. 0

    Which version of Python are you using? int should convert strings such as '040' just fine.

    Python 3.9.13 | packaged by conda-forge | (main, May 27 2022, 16:56:21) 
Type 'copyright', 'credits' or 'license' for more information
IPython 8.4.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: int('040')
Out[1]: 40

In [2]:

    Are you by any chance typing int(040) instead of int('040')? One is a decimal integer literal while the latter is a string.

    Leading zeros are not allowed in Python?

    Using python 3.9.13, your code works without problems.

    voltage = "V040038038039C125067"

v1 = voltage[1:4]
v2 = voltage[4:7]
v3 = voltage[7:10]
v4 = voltage[10:13]

volt_1 = int(v1)/10
volt_2 = int(v2)/10
volt_3 = int(v3)/10
volt_4 = int(v4)/10

print(v1, v2, v3, v4, volt_1, volt_2, volt_3, volt_4)
# 040 038 038 039 4.0 3.8 3.8 3.9
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  3. 0

    Use a regex to get a list of 6 string values from your sql data (grouped by 3 digits).

    The most efficient way to use the regex is to compile it at the beginning then use the compiled regex on your sql rows.

    Use a list-comprehension to obtain a list of floats (converted from strings, also stripping the leading zeros).

    Use sequence unpacking to separate into a voltage list and a current list.

    import re

pattern = re.compile(r"(d{3})")
data = "V040038038039C125067"
values = [int(x.lstrip("0")) / 10.0 for x  in pattern.findall(data)]
voltage, current = values[:4], values[4:]
print(voltage, current)  # [4.0, 3.8, 3.8, 3.9] [12.5, 6.7]

    You can make a function of that, to easily apply to your sql rows.

    def parse(data):
    values = [int(x.lstrip("0")) / 10.0 for x  in pattern.findall(data)]
    return values[:4], values[4:]

voltage, current = parse("V040038038039C125067")
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