Re: Two-dimensional map
- Posted by mattlewis (admin) Jan 31, 2013
- 1247 views
I need structure similar to two-dimensional array, but with text indexes. How to organize such map? For example, X-keys are employees and Y-keys are assets. Value is deprecation factor.
"John Smith", "Chair" --> 0.50 "John Smith", "Computer" --> 0.99 "Kevin Fogg", "Chair" --> 0.78 "Kevin Fogg", "Computer" --> 1.5 -- he updated software at own expense
I see almost tree ways:
1. Regular map, where each key is concatenated coordinates. So, I need use key User&Stuff. It isn't so silly. I don't need to break a line in the future.
put(Deprecation, "John SmithChair", 0.50) put(Deprecation, "John SmithComputer", 0.99) put(Deprecation, "Kevin FoggChair", 0.78) put(Deprecation, "Kevin FoggComputer", 1.5)
2. The similar way, but keys unite in sequence of lines, instead of in one line.
put(Deprecation, {"John Smith", "Chair"}, 0.50) put(Deprecation, {"John Smith", "Computer"}, 0.99) put(Deprecation, {"Kevin Fogg", "Chair"}, 0.78) put(Deprecation, {"Kevin Fogg", "Computer"}, 1.5)
I would prefer 2 over 1, since it seems cleaner.
3. Nested maps. In other words, map of maps. I suspect that this way is ideologically best. However it is the most difficult. I will accept also the first method. I need to thrust data to "cell of array" and then to get them, having both keys. Search all values with only one of keys, search key by value, or something similar isn't required to me. What way you will advise to me?
Why do you think that nested maps would be difficult? We have nested_put and nested_get for doing exactly this.
I might suggest something like the following, which allows you to look things up by either asset or employee:
include std/map.e map employees = map:new() map assets = map:new() map depreciations = map:new() public procedure add_depreciation( sequence employee_name, sequence asset_name, atom depreciation_value ) map:nested_put( employees, {employee_name, asset_name}, 1 ) map:nested_put( asset_name, {asset_name, employee_name}, 1 ) map:put( depreciations, { employee_name, asset_name }, depreciation_value ) end procedure public function get_depreciation( sequence employee_name, sequence asset_name ) return map:get( depreciations, { employee_name, asset_name }, 0 ) end function public function get_employee_depreciations( sequence employee_name ) sequence employee_depreciation = {} atom emp_map = map:get( employees, employee_name ) if map( emp_map ) then sequence employee_assets = map:keys( emp_map ) for i = 1 to length( employee_assets ) do employee_depreciation = append( employee_depreciation, { employee_assets[i], map:get( depreciations, { employee_name, employee_assets[i] }, 0 ) } ) end for end if return employee_depreciation end function public function get_asset_depreciations( sequence asset_name ) sequence asset_depreciation = {} atom asset_map = map:get( assets, asset_name ) if map( asset_map ) then sequence asset_employees = map:keys( asset_map ) for i = 1 to length( asset_employees ) do asset_depreciation = append( asset_depreciation, { asset_employees[i], map:get( depreciations, { asset_employees[i], asset_name }, 0 ) } ) end for end if return asset_depreciation end function
Matt
