Plot the density of submissions over time.
plot_activity( history, baseline = "baseline", col = 1:length(history), alpha.f = 0.7, bw = 3600 * 24, by = 4, xlab = "Date", ylab = "Submissions intensity", bty = "l", fg = "darkslategray", col.axis = fg, col.lab = fg, text.col = fg, ... )
| history | list of the submissions history per team as returned by   | 
    
|---|---|
| baseline | string. name of the team considered as the baseline that will not be plotted.  | 
    
| col | colors of the teams.  | 
    
| alpha.f | factor modifying the opacity alpha of colors; typically in [0,1].  | 
    
| bw | real. the smoothing bandwidth to be used by   | 
    
| by | real. height of the interval between two teams in number of submissions.  | 
    
| xlab, ylab | axis labels. see   | 
    
| bty, fg, col.axis, col.lab | graphical parameters. see   | 
    
| text.col | the color used for the legend text. see   | 
    
| ... | further parameters passed to   | 
    
NULL