Simple List question. HELP.
- To: mathgroup at smc.vnet.net
- Subject: [mg39389] Simple List question. HELP.
- From: "Daniel Heneghan" <dhenegha at bway.net>
- Date: Thu, 13 Feb 2003 04:55:38 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
I am new to Mathematica. This is vexing. All I want to do is create a
2-dimensional list so that I can enter x,y values and then plot the
list. I want to do this programmatically. I am having such incredible
trouble trying to accomplish this simple task. I know that there is
probably a Mathematica optimized way to do this, but I and trying to
write a little program and for now I want to stay with paradigms that I
am familiar with. Here is what I have been doing.
Create a 2 dimensional list.
In[532] lst={{}}
Out[532]= {{}}
Enter the first pair into the first place in the list.
In[533]:= lst[1]={{0,1}}
Errors and beeps here, but it does seem to record the correct values.
Set::write: Tag List in {{}}[1] is Protected.
Out[533]={{0,1}}
Add anoter pair of values.
In[534]:= lst=Append[lst,{{1,2}}]
Out[534]= {{},{{1,2}}}
The second pair is OK, but the first pair has been obliterated.
Add another pair. Now all subsequent entries are OK, but I still have
lost the first pair.
In[535]:= lst=Append[lst,{{2,c}}]
Out[535]= {{},{{1,2}},{{2,c}}}--
What is going on? What are the mysteries of working with lists in
Mathematica. In any programming language this is simple. I can't grasp
it in Mathematica. The reason I need to do this is that for the list
plot I need the x values to start at 0 not 1.
Thanks,
Daniel Heneghan
Ceara Systems
(212) 696-9208
ceara at bway.net
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