[R] plot only partial plots

[Monica Palaseanu-Lovejoy]

Hi everybody,

I would like to plot only a part of a data frame, and identify the 
IDs for all the points with  values higher than a certain value. I 
will try to be more explicit: 

I did a qqnorm plot of my data. It is obvious from the plot that 
all the sample quantiles which are in Theoretical Quantiles = or > 
than 1 belong to another group. To be sure about that I plot the 
cooks.distance for the same data, and sure enough the data with 
the indices grater than 250 (x axis) have obvious higher Cook ‘s 
distance than the majority of the data. The data indices on the 
Cook’s distance plot are different than my data ID (in my data 
table) which is “character type”. How do I identify the IDs of the 
data I am interested into, and how I can plot only the data with 
Theoretical Quantiles equal or grater than 1? 

And, of course, how can I plot only the Cook’s distance for the 
data with indices higher than a certain number, or Cook’s 
distance higher than a certain number????

And, on the same line, how can I sort a tab-delimited table after 
the values from one column? I know how to assign one column 
to a vector and sort that vector, but what if I want to sort the 
whole table, like in Excel for example?

Thank you in advance for all your time and answers,

Monica


Monica Palaseanu-Lovejoy
University of Manchester
School of Geography
Mansfield Cooper Building 
Oxford Road, Manchester
M13 9PL, UK. 
email: monica.palaseanu-lovejoy at stud.man.ac.uk