waterfallplots: how to plot individual bars starting at '0' y-axis?

[BhaktiDwivedi]

I am trying to generate waterfallplots using your R package {waterfall}.

I have the below data frame (df) (sample data)

id value subgroup
1 -5.31 10
2 -3.73 10
3 -3.53 10
4 -3.21 10
5 -2.96 10
6 -2.66 20
7 -0.05 20
8 2.5 20
9 3 20
10 5 20

I use the below command to begin with:

waterfallchart(df[,2]~df[,1], data=df, names.arg=NULL, col=c("red","black"), level.lines=FALSE, groups=subgroup)

I am running into following:
(a) I do not get the bars from '0' value (y-axis) starting point, rather it's plotting cumulative row (r) values (r1, r1+r2, r1+r2+r3, r1+r2+r3+r4 and so on) when plotting individual bars. Is there a way to fix that? How can I simply plot the values as in 'value' column?
(b) How can I color each bar by the subgroup category? Is the col command ok?
(c) How can I remove the x-axis names. The 'names.arg=NULL' doesn't seem to work

I would greatly appreciate your help or suggestions on above. Thank you!!

Regards,
Bhakti