[R] row subtraction

I don't know if there is a way to do this in R but I want to subtract within the same column from different rows. I want to subtract c(r)-c(r-1) and continue down the column until they are all calculated and form another column. Again I don't know if R can do this but I thought I would ask. T

[R] ScatterPlot

I am trying to make a scatterplot with containing three columns. I know how to plot the two columns but now the third column consists of M or F (male or female) and I don't know how to separate the data so I can make two separate regression lines on the same graph. meta #name of file plot(me