[R] removing rows from a matrix using condition within groups

[swam]

I am needing some help in removing certain rows in a data.matrix and then do
some calculation. So Iam need to removing certain values above a threshold
or value from another  vector.

For eg.. in the below data matrix X there are 6 groups (A, B, C, D, E ,F)

>X
rows	groups	values
1	A	1.2
2	A	0.2
3	A	6
4	A	0.5
5	A	22
6	B	0.2
7	B	1
8	C	0.5
9	D	5
10	D	4
11	D	40
12	E	0.3
13	E	0.5
14	E	1
15	E	1.1
16	E	0.9
17	E	4
18	F	0.22
19	F	0.32
20	F	1.5


I have another array  Y with 6 values (equal to the number of groups in X). 
I need to remove the rows in each group in X that is greater than the first
value in Y for Group A in X and similarly for group B and so on…..

>Y


A	1.5
B	1.1
C	0.8
D	6
E	2
F	1.9


For eg… any value greater than 1.5 (from vector Y) must be removed in Matrix
X  only for group A. similarly for all, hence the result will be like the
matrix shown below…

rows	groups	values
1	A	1.2
2	A	0.2
3	A	6
4	A	0.5
5	B	0.2
6	B	1
7	C	0.5
8	D	5
9	D	4
10	E	0.3
11	E	0.5
12	E	1
13	E	1.1
14	E	0.9
15	F	0.22
16	F	0.32
17	F	1.5


I tried to get this with no luck any help would be appreciated.

swam


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