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P: 1
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Hi,
I have in my program a list of lists of variables. These variables change as the program runs. I would like to be able to link meaningful names to the variables. So, say I have a list of quantities of different coins in my possession
where the entries are the quantities of pennies, nickels, dimes, and quarters I have, respectively. Can I assign variable names to the entries so that if, in the course of my program, it simulates a purchase for 5 cents- -
myChange [3] = myChange [3] - 1
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myChange [2] = myChange [2] + 2
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I can say -
print quarters
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print dimes
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And get the following output?
0
2
Thanks for the help; sorry if my terminology is bad as I am new to programming!
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| Expert 5K+
P: 6,596
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Hi,
I have in my program a list of lists of variables. These variables change as the program runs. I would like to be able to link meaningful names to the variables. So, say I have a list of quantities of different coins in my possession
where the entries are the quantities of pennies, nickels, dimes, and quarters I have, respectively. Can I assign variable names to the entries so that if, in the course of my program, it simulates a purchase for 5 cents-
-
myChange [3] = myChange [3] - 1
-
myChange [2] = myChange [2] + 2
-
I can say
-
print quarters
-
print dimes
-
And get the following output?
0
2
Thanks for the help; sorry if my terminology is bad as I am new to programming!
Your terminology (and use of this site) is excellent for a beginner!
You could achive 100% of your goal (getting a reference to an array item) using an extension called scipy. A 99% solution with native lists requires that you unpack the list each time you want to use it. It's a technique that I use often: -
>>> aList = [1, 2, 3, 4]
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>>> pennies, nickles, dimes, quarters = aList
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>>> quarters
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4
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>>>
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| Expert Mod 2.5K+
P: 2,851
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You may consider using a class for your program. This is a start: - class myChange(object):
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def __init__(self, penny=0, nickel=0, dime=0, quarter=0):
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self.penny = penny
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self.nickel = nickel
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self.dime = dime
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self.quarter = quarter
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self.data = [penny,nickel,dime,quarter]
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self.__init = 1
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def __getitem__(self, i):
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return self.data[i]
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def __setitem__(self, i, value):
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try:
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object.__setattr__(self, {0:'penny',1:'nickel',2:'dime',3:'quarter'}[i], int(value))
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object.__setattr__(self, 'data', [int(self.penny), int(self.nickel), int(self.dime), int(self.quarter)])
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except KeyError:
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raise IndexError, "Index argument out of range in '%s' __setitem__" % (type(self).__name__)
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except ValueError:
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raise ValueError, "Invalid literal in '%s' __setitem__" % (type(self).__name__)
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def __setattr__(self, name, value):
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if not self.__dict__.has_key('_myChange__init'):
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return object.__setattr__(self, name, value)
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elif self.__dict__.has_key(name):
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object.__setattr__(self, name, value)
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object.__setattr__(self, 'data', [int(self.penny), int(self.nickel), int(self.dime), int(self.quarter)])
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else:
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raise AttributeError, "'%s' object has no attribute '%s'" % (type(self).__name__, name)
Here is some interaction: - >>> myChange(6,4,7,2)
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<__main__.myChange object at 0x00F972D0>
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>>> chg = myChange(6,4,7,2)
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>>> chg.penny
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6
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>>> chg.penny = 12
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>>> chg.data
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[12, 4, 7, 2]
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>>> chg.quarter += 7
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>>> chg.quarter
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9
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>>> chg.data
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[12, 4, 7, 9]
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>>> chg[3]=3
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>>> chg.quarter
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3
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>>> chg[3]
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3
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>>> chg[4]
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Traceback (most recent call last):
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File "<interactive input>", line 1, in ?
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File "C:\SDS2_7.0\macro\Work In Progress\myChange.py", line 13, in __getitem__
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return self.data[i]
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IndexError: list index out of range
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>>>
| | | |  Question stats - viewed: 1500
- replies: 2
- date asked: Jul 30 '07
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