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project-3-draft [2021/04/22 12:04] pdmatei |
project-3-draft [2021/04/25 16:07] (current) roxana_elena.stiuca prerequisite for taskset3 |
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| | Cartesian (Row -> Row -> Row) [String] Query Query | | Cartesian (Row -> Row -> Row) [String] Query Query | ||
| | Projection [String] Query | | Projection [String] Query | ||
| - | -- | forall a. Filter (FilterCondition a) Query | + | | forall a. FEval a => Filter (FilterCondition a) Query |
| - | | Graph EdgeOp query | + | | Graph EdgeOp Query |
| | | ||
| -- where EdgeOp is defined: | -- where EdgeOp is defined: | ||
| Line 34: | Line 34: | ||
| **Don't worry about Graph or Filter queries yet.** | **Don't worry about Graph or Filter queries yet.** | ||
| - | + | ==== Prerequisite ==== | |
| + | Add the following lines at the beginning of your .hs files: | ||
| + | <code haskell> | ||
| + | {-# LANGUAGE ExistentialQuantification #-} | ||
| + | {-# LANGUAGE FlexibleInstances #-} | ||
| + | </code> | ||
| + | |||
| + | The first line allows ''forall a''. | ||
| + | The second allows ''instance FEval String''. | ||
| ===== Query Evaluation ===== | ===== Query Evaluation ===== | ||
| Line 130: | Line 139: | ||
| The query ''Graph edgeop query'': creates such a table starting from the result of the evaluation of ''query''. Suppose the query evaluates to a table **T**. | The query ''Graph edgeop query'': creates such a table starting from the result of the evaluation of ''query''. Suppose the query evaluates to a table **T**. | ||
| - | * The nodes are the rows in table **T**. | + | * The nodes are the **rows** in table **T**. |
| * The weight of an edge between 2 nodes is given by ''edgeop'', which returns a ''Maybe Value''. If ''edgeop row1 row2'' returns ''Nothing'', then we don't have an edge between those 2 nodes. If it returns ''Just val'' then we have an edge between ''row1'' and ''row2'' of weight ''val''. | * The weight of an edge between 2 nodes is given by ''edgeop'', which returns a ''Maybe Value''. If ''edgeop row1 row2'' returns ''Nothing'', then we don't have an edge between those 2 nodes. If it returns ''Just val'' then we have an edge between ''row1'' and ''row2'' of weight ''val''. | ||
| * In the resulting table, each row describes an edge between node_i and node_j and will have the values: | * In the resulting table, each row describes an edge between node_i and node_j and will have the values: | ||
| Line 138: | Line 147: | ||
| The edge //node_i-node_j// is the same as //node_j-node_i//, so it should only appear once (graphs are unoriented). "From" value should be lexicographically before "To". | The edge //node_i-node_j// is the same as //node_j-node_i//, so it should only appear once (graphs are unoriented). "From" value should be lexicographically before "To". | ||
| + | |||
| + | **Example:** Suppose **T** is the table shown below: | ||
| + | <code> | ||
| + | Name Grade Class | ||
| + | Mihai 9 321 | ||
| + | Andrei 8 322 | ||
| + | Stefan 10 321 | ||
| + | Ana 9 322 | ||
| + | </code> | ||
| + | |||
| + | If we would like to build a graph that connects all students in the same class, then: | ||
| + | <code haskell> | ||
| + | edgeop [_,_,z] [_,_,c] | ||
| + | | z == c = Just c | ||
| + | | otherwise = Nothing | ||
| + | </code> | ||
| + | |||
| + | and the resulting graph will be: | ||
| + | <code> | ||
| + | From To Value | ||
| + | Mihai Stefan 321 | ||
| + | Ana Andrei 322 | ||
| + | </code> | ||
| + | |||
| + | If we would like to build a graph that connects students with grades equal or with a difference of **at least** a point, then: | ||
| + | <code haskell> | ||
| + | edgeop [_,x,_] [_,y,_] | ||
| + | | abs $ (read x :: Int) - (read y :: Int) <= 1 = Just "similar" | ||
| + | | otherwise = Nothing | ||
| + | </code> | ||
| + | |||
| + | and the resulting graph is: | ||
| + | <code> | ||
| + | From To Value | ||
| + | Andrei Mihai similar | ||
| + | Mihai Stefan similar | ||
| + | Ana Mihai similar | ||
| + | Ana Andrei similar | ||
| + | Ana Stefan similar | ||
| + | </code> | ||
| + | |||
| ==== Similarities graph, using queries ==== | ==== Similarities graph, using queries ==== | ||
| + | |||
| We want to check the similarities between students lecture points. | We want to check the similarities between students lecture points. | ||
| * For that, we want to obtain a graph where "From" and "To" are students' emails and "Value" is the distance between the 2 students' points. | * For that, we want to obtain a graph where "From" and "To" are students' emails and "Value" is the distance between the 2 students' points. | ||
| Line 145: | Line 196: | ||
| * The edges in the resulting graph (the rows in the resulting table) should be sorted by the "Value" column. If email is missing, don't include that entry. | * The edges in the resulting graph (the rows in the resulting table) should be sorted by the "Value" column. If email is missing, don't include that entry. | ||
| - | Your task is to write ''similarities_query'' as a sequence of queries, that once evaluated results in the graph described above. | + | Your task is to write ''similarities_query'' as a **sequence of queries**, that once evaluated results in the graph described above. |
| + | |||
| + | **Note**: ''similarities_query'' is a Query. The checker applies ''eval'' on it. | ||
| ===== TL;DR Tasks ===== | ===== TL;DR Tasks ===== | ||
| - | - Enroll Query in class Eval (without Filter or Graph). 0.3p | + | - Enroll ''Query'' in class ''Eval'' (without ''Filter'' or ''Graph''). **0.3p** |
| - | - Enroll FilterCondition in class FEval and implement eval for Filter query. 0.2p | + | - Enroll ''FilterCondition'' in class ''FEval'' and implement ''eval'' for ''Filter'' query. **0.2p** |
| - | - Implement eval for Graph query. 0.2p | + | - Implement ''eval'' for ''Graph'' query. 0.2p |
| - | - Get graph for similarities. 0.3p | + | - Extract similarity graph. 0.3p |
| ===== Checker ===== | ===== Checker ===== | ||