I have employment data which are huge - about 500 data for each category, like agriculture field, fishing field etc. Now I want to categorise this data in to 7 ranges. Suppose <50=1, >50-100=2, etc. for producing an agriculture map of a country by showing these categories as a legend. I don't want to change my main GIS data. I only want to show this data into small categories in Map. How can I do it?
I suppose you want to do this in ArcMap.
Right click -> Properties -> Symbology
You will need to select the
Classified and finally classify in the way you want.
For more info check the ESRI help file
If I got you right, you might use grouping techniques in Layer Properties dialog box > Symbology tab > Categories. Here you would specify the classifications (0>50, 50>100 etc) and labels (1,2,3 etc). The legend in the layout view will use the labels you've specified, so you don't have to change anything in the underlying data.