Hi All:

Greetings, and best wishes from the festive times here at Kolkata, India -- the time of Durga Puja celebrations. 

I seek your advice as I try plotting lines for my data. The problem:

I have created a dataframe that looks like this (name: myFrame):

          lowest second third fourth highest    significance
INAS      0.107  0.115 0.123  0.115   0.166 0.000
MMA       0.091  0.107 0.115  0.142   0.179 0.000
DMA       0.126  0.103 0.126  0.129   0.142 0.031

The numbers in the dataframe indicate values of a continuous variable INMET (indicating ratio of inorganic arsenic vesus methylated arsenic species) for the respective quintiles of variables INAS, MMA, and DMA; "lowest" through "highest" indicate quintile levels of INAS, 
MMA, and DMA. INAS, MMA, and DMA are discrete ordinal variables (factors, each variable has following levels: lowest, ..., highest). Significance indicates significance levels. 

>From this dataframe, I want to plot INAS, MMA, and DMA (x-axis : levels "lowest" through "highest", y-axis: values of INMET) as separate lineplots in the same graphic window. I can individually plot lines for INAS,MMA, and DMA; however, I want the three lines to appear in the same graph (say in different colors). 

Searching the archives and the documentation, I got to interaction.plot(), but this is not what I want. 

I can export the dataframe to a spreadsheet program and can draw such a graph (one graph with multiple lines, one for INAS, one for MMA, and one for DMA), but would prefer to do it in R. 

I looked for, but could not locate how to do that in either the R documentation, or the archives of mailing list postings. I suspect I am missing something very obvious; if there is a solution that I was inept to look up in the documentation or archives, I duly apologize.

Would greatly appreciate your advice.

Kind regards,
Arin Basu

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