lookup-tables

I'm trying to find the best way to implement a QHash-like lookup table that uses multiple keys to return one value. I have read that the Boost library has similar functionality, but I would like to avoid this if possible. An example of what I would like to do is as follows (obviously the following pseudo-code is not possible): //First key (int) - Engine cylinders //Second key (int) - Car weight //Value (int) - Top speed MyLookup<int, int, int> m_Lookup m_Lookup.insert(6, 1000, 210); m_Lookup.insert(6, 1500, 190); m_Lookup.value(6, 1000); //Returns 210 My first (and extremely slow) idea was to

I'd like to create a table lookup formula that matches two columns. For instance, suppose I'd like to find the value of the Letter column at the row where the Type column is Biennial and the Result column is Warning . A B C 1 Letter Type Result 2 A Annual Exceeds 3 B Biennial Warning 4 C Biennial DevelopmentNeeded 5 D Biennial PartiallyMeets 6 E Annual Meets What would the formula look like to accomplish this? oscarius The SUMPRODUCT() formula is really apt for situations where you want to lookup a value with multiple criteria. It is most convenient when wanting to look up numeric values, but

I am trying to make a simple LookUpTable based on an array of integers, where the idea is to have it calculated at compile time . Trying to make it possible to use it for any other future tables of various integer types I might have, I need it as a template . So I have a LookUpTable.h #ifndef LOOKUPTABLE_H #define LOOKUPTABLE_H #include <stdexcept> // out_of_range template <typename T, std::size_t NUMBER_OF_ELEMENTS> class LookUpTableIndexed { private: //constexpr static std::size_t NUMBER_OF_ELEMENTS = N; // LookUpTable T m_lut[ NUMBER_OF_ELEMENTS ] {}; // ESSENTIAL T Default Constructor for

This question is related to this . Let x be an 8 bit integer. I will number bits from left to right because that's how we read. If I want to get the third and fifth bits and put them in the first and second bits, with everything else as zero, I can have f(x) = (5*x) & 0b11000000 . More concisely: 00a0b000 -> ab000000 | f_0b00101000(x) = (5*x) & 0b11000000 However if I want the fifth, sixth and eighth bits to be in the first three bits, f(x) is different: 000ab0cd -> abcd0000 | f_0b00011011(x) = ((x << 3) & 0b11000000) | (x << 4) Note that the n in f_n(x) indicates which bits I care about. n

I'm currently using (or trying to use) a lookup table to represent a column that contains an enumerated string. I've had extensive discussions with my team to make sure this is the direction we want to go and have decided to pursue it but unfortunately none of us know how to tie the lookup table to the column using migrations and if there are changes that have to be made in the model/controller/views to support this new behavior. I've googled this extensively and have not found good examples of doing this so I'm hoping someone can either tell me of a wonderful link to a tutorial I just missed

I need to compute the mathematical expression floor(ln(u)/ln(1-p)) for 0 < u < 1 and 0 < p < 1 in C on an embedded processor with no floating point arithmetics and no ln function. The result is a positive integer. I know about the limit cases (p=0), I'll deal with them later... I imagine that the solution involves having u and p range over 0..UINT16_MAX , and appeal to a lookup table for the logarithm, but I cannot figure out how exactly: what does the lookup table map to? The result needs not be 100% exact, approximations are OK. Thanks! Since the logarithm is used in both dividend and

I have a bunch of tables like this: Lookup_HealthCheckupRisks ------------ ID Name 1 Anemia 2 Anorexic 3 Bulemic 4 Depression ... 122 Syphilis PatientRisksOnCheckup ------------------ ID CheckupID RiskID 1 11 2 2 11 3 3 12 1 4 14 1 5 14 3 ... But I need a flattened version, like this: PatientCheckup ------------------ CheckupID Risk_1 Risk_2 Risk_3 Risk_4 .. Risk_122 11 0 1 1 0 0 12 1 0 0 0 0 13 0 0 0 0 0 14 1 0 1 0 0 I'm clueless how to do this, the best I can think of is to write a temp table, define all 122 columns, and then do If Exists ( SELECT * FROM PatientRisksOnCheckup where RiskID=i