[R] how to reduce in a grid ?

[Norbert]

hi dear R users,
I'm a newbie with R and excuse me if my question is stupid ...  but i've read lot of documentation and I don't know how to do.

I have a dataset like

x    y    var1    var2
2    4    10    50
3   3    20    70
3    2    50    68
4    5   34    42
5    3    10    23
7    8    23    42
7   3    23    34
[...]

And I need to produce grids like :
y\x    ]0-2]    ]2-4]    ]4-6]    ]6-8]
]0-3]   
]3-6]            means of corresponding values for var1 (or var2)
]6-9]


but I don't find any example ....


in advance, lot of thanks for your help

js



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