multiplication of dimensional analysis

[msaenz]

:mrgreen: hi im am tryingto create a dimensional analysis thing going on and so far i have this

def mult(self,other):
        tempTuple1=list()
        tempTuple2=list()
       
        i=0
        for unit,value in other.expr:
            for unit2,value2 in self.expr:
                if unit2 == unit:
                    tempTuple1.append((unit, value+value2))
                    #self.expr[i]=tempTuple1
                    
                   
##        for unit2,value2 in self.expr:
##            for unit,value in other.expr:
##                if unit2 != unit:
##                   tempTuple1.append((unit2,value2))


        print tempTuple1

and my output is so far like this:
>>> t = dimensions([('j',2),('km',1), ('f',5)])
>>> w = dimensions([('j',2),('f',1)])
>>> w.mult(t)
[('j', 4), ('f', 6)] need to append km1.... what am i doing wrong anyone? thanks for your help

[Ene Uran]

You need to give us more of your code, otherwise this will be an exercise in mind reading!

[msaenz]

class dimensions:
def __init__(self, listofTuples):
self.expr = listofTuples
 
def sub(self,other):
for value in self.expr:
if not value in other.expr:
return "incompatible"

return self.expr
def mult(self,other):
tempTuple1=list()
tempTuple2=list()

i=0
for unit,value in other.expr:
for unit2,value2 in self.expr:
if unit2 == unit:
tempTuple1.append((unit, value+value2))
tempTuple2.append(())

## for unit2,value2 in self.expr:
## for unit,value in other.expr:
## if unit2 != unit:
## tempTuple1.append((unit2,value2))
 
#print tempTuple1

here is my code now, i hope this is better

[Ene Uran]

I don't know what editor you are using, but for some odd reason you lost all the indentations (critical for Python to work). I doctored up your code and added a number of temporary print statements, always good for troubleshooting. I noticed that your mult() has no return statement, so result = None is the returned.
Here is the doctored code:

class dimensions:
    def __init__(self, listofTuples):
        self.expr = listofTuples
 
    def sub(self, other):
        for value in self.expr:
            if not value in other.expr:
                return "incompatible"
            return self.expr

    def mult(self, other):
        tempTuple1=list()
        tempTuple2=list()
        print tempTuple1 # []
        print tempTuple2 # []
        print other.expr # [('j', 2), ('km', 1), ('f', 5)]
        print self.expr  # [('j', 2), ('f', 1)]

        i=0
        for unit,value in other.expr:
            for unit2,value2 in self.expr:
                if unit2 == unit:
                    tempTuple1.append((unit, value+value2))
                    tempTuple2.append(())

##      for unit2,value2 in self.expr:
##          for unit,value in other.expr:
##              if unit2 != unit:
##                  tempTuple1.append((unit2,value2))
 
        print tempTuple1 # [('j', 4), ('f', 6)]
        print tempTuple2 # [(), ()]
        # what does mult() return?????

t = dimensions([('j',2),('km',1), ('f',5)])
print t # <__main__.dimensions instance at 0x00AE6BE8>
w = dimensions([('j',2),('f',1)])
print w # <__main__.dimensions instance at 0x00AE6EE0>
print w.mult(t) # gives None, correct since there is no return

How new are you to Python?

[msaenz]

sorry i just copied it and pasted it from my textedit. i was using the command line in gentoo.... i was working mostly with biopython and zope, never really persay did simple things in python. i just kinda skipped that and learned biopython syntax and the necessary python syntax to do my internship.

what i would like it to return is this: for example:
t = dimensions([('j',2),('km',1), ('f',5)])

w = dimensions([('j',2),('f',1)])

print w.mult(t) # gives None, correct since there is no return
return tempTuple1.append(the value that does not have a pair to be added with ('km',1)]

([('j',4),('f',6),('km',1)])

thanks for your help. what book would you recommend to learn python? i read some of the tutorials and they help but a book would be good.

[vegaseat]

To get a hang of the basics of Python, I would recommend the book "Learning Python" by Mark Lutz and David Ascher, published by O'Reilly (no relation to the buffoon on TV!)

[msaenz]

still can't figure out how to append the last list into a tuple...does anyone stillhave any ideas. i tried popping and appending what was left and so forth. and yeah...still stuck any more ideas thanks!