parameters from variable?

Question

I am new to python and i am trying to read each line of file with comma ',' separated values. like this line:

435,567,897,905,6,56,22,90.

My existing code

#!/usr/bin/python

class Line():
    def __init__(self, val1, val2, val3, val4, val5, val6, val7, val8):
        self.val1 = val1
        self.val2 = val2
        self.val3 = val3
        self.val4 = val4
        self.val5 = val5
        self.val6 = val6
        self.val7 = val7
        self.val8 = val8

    def display(self):
        print("CPU:",self.val1)

file = open("/Users/user/Desktop/data.txt", 'r')

for line in file:
 line = line.split(",")
 li = str(line)[1:-1]
 lin = Line(li)
 lin.display()

file.close()

data.txt is like below.

435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90
435,567,897,905,6,56,22,90

Please help me how to print first value like CPU:value.

Answer 1

You need to pass each of the items in each line to the Line constructor. One way to do it would be to write:

li = Line(line[0], line[1], line[2], line[3], line[4], line[5], line[6], line[7]))

but that's a lot of writing. Python has a shortcut:

li = Line(*line)

which will do the same thing.

Not sure why you were using str(line)[1:-1]...

Anyway, this means your code could be re-written to look like the following which also use a with statement which will automatically close the file after the loop:

class Line():
    def __init__(self, val1, val2, val3, val4, val5, val6, val7, val8):
        self.val1 = val1
        self.val2 = val2
        self.val3 = val3
        self.val4 = val4
        self.val5 = val5
        self.val6 = val6
        self.val7 = val7
        self.val8 = val8

    def display(self):
        print("CPU:", self.val1)

with open("/Users/user/Desktop/data.txt", 'r') as file
    for line in file:
        line = line.split(",")
        lin = Line(*line)
        lin.display()

Answer 2

To unpack the values in a list into all the arguments of a function (in this case Line.__init__), use the * operator, like so:

lin = Line(*li)