Generate random samples at a certain point

I have the following two data set:

  A=  (1,1)       1.9643
 (2,1)       2.2753
 (3,1)       2.9781
 (4,1)       2.9320
 (5,1)       3.5772
 (6,1)       4.0150
 (7,1)       3.3814
 (8,1)       3.9113
 (9,1)       2.7822
(10,1)       2.5518
(11,1)       3.3698
(12,1)       3.1048
(13,1)       1.9182
(14,1)       2.2638
(15,1)       2.6555
(16,1)       3.1855
(17,1)       3.6579
(18,1)       3.9113
(19,1)       3.6002
(20,1)       3.0357
(21,1)       1.5841
(22,1)       2.0103
(23,1)       1.9527
(24,1)       2.2753
(25,1)       2.3099
(26,1)       2.8283
(27,1)       3.0473
(28,1)       2.4827
(29,1)       2.5057
(30,1)       1.8721
(31,1)       2.0103
(32,1)       1.2269
(33,1)       1.8951
(34,1)       1.5610
(35,1)       1.5495
(36,1)       1.6878
(37,1)       1.4919
(38,1)       0.9620
(39,1)       1.1693
(40,1)       0.8122
(41,1)       0.9735
(42,1)       1.2500
(43,1)       1.3191
(44,1)       2.2292
(45,1)       2.4482
(46,1)       2.7938
(47,1)       2.0910
(48,1)       2.5403
(49,1)       0.9044
(50,1)       0.7662
 (1,2)       4.5957
 (2,2)       3.8589
 (3,2)       4.5651
 (4,2)       3.5519
 (5,2)       2.8560
 (6,2)       3.1937
 (7,2)       3.4291
 (8,2)       4.1761
 (9,2)       4.0431
(10,2)       4.6162
(11,2)       3.9101
(12,2)       3.0709
(13,2)       4.0534
(14,2)       4.3706
(15,2)       3.5008
(16,2)       4.2888
(17,2)       3.8692
(18,2)       3.4291
(19,2)       3.1221
(20,2)       3.3165
(21,2)       3.3575
(22,2)       3.2039
(23,2)       2.7843
   (24,2)       2.7127
(25,2)       2.9584
(26,2)       2.6309
 (27,2)       2.2931
  (28,2)       2.0373
   (29,2)       2.3853
   (30,2)       2.0577
   (31,2)       2.3546
    (32,2)       2.3239
    (33,2)       2.9174
     (34,2)       3.0709
    (35,2)       2.6923
     (36,2)       2.4057
     (37,2)       2.0271
      (38,2)       2.6820
   (39,2)       2.9276
    (40,2)       2.9992
   (41,2)       3.3881
   (42,2)       3.1937
   (43,2)       3.5109
   (44,2)       2.2010
  (45,2)       2.6411
  (46,2)       1.9656
   (47,2)       1.6177
  (48,2)       2.8867
 (49,2)       3.0198
 (50,2)       2.5899

Here, A is two dimensional sparse matrix where (i,i).

And B is (50,1) matrix, where the first 20 values are +1 and last 30 values are -1.

So the data point is look like this:

Now, I want to choose the (40,50) position of A and then want to generate 1000 random points within +/- 2 regions of the points.

So, the graph should be something like this:

Please let me know, how can I do it.