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Questions tagged [lookup-tables]

A look-up table is an array or matrix of data that contains items that can be searched. Lookup tables may be arranged as key-value pairs, where the keys are the data items being searched (looked up) and the values are either the actual data or pointers to where the data are located.

A look - up table is an array or matrix of data that contains items that are searched. Lookup tables may be arranged as key-value pairs, where the keys are the data items being searched (looked up) and the values are either the actual data or pointers to where the data are located.

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Is there a convenient way to apply a lookup table to a large array in numpy?

I’ve got an image read into numpy with quite a few pixels in my resulting array. I calculated a lookup table with 256 values. Now I want to do the following: for i in image.rows: for j in image.cols: mapped_image[i,j] =…
Profpatsch
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Lookup table vs switch in C embedded software

In another thread, I was told that a switch may be better than a lookup table in terms of speed and compactness. So I'd like to understand the differences between this: Lookup table static void func1(){} static void func2(){} typedef enum { …
Plouff
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gcc warning: braces around scalar initializer

I have look-up-table as defined below and I'm making use of GCC. When I compile I get warnings as warning: braces around scalar initializer What does this warning mean? How should I initialize this LUT? Am I making a mistake in initializing this…
HaggarTheHorrible
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TSQL table variable initialization

I have the following TSQL table variable: declare @NumDaysMonth table ( month_id smallint, num_days smallint ) I just want a quick look-up for the number of days in each month. How can I initialize this table like a C array: int…
CodeKingPlusPlus
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Is there a simple way to create a javascript lookup table?

I'm looking for a simple way of looking up a value, using javascript, against a number of dimensions: eg. (I'm going to use products and product options to describe this, the data is coming from a database in a very similar format) Colour Size…
Paul
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Fastest possible string key lookup for known set of keys

Consider a lookup function with the following signature, which needs to return an integer for a given string key: int GetValue(string key) { ... } Consider furthermore that the key-value mappings, numbering N, are known in advance when the source…
Pavel Minaev
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Java 8 - store lambdas in List

I wonder if it's possible to store lambdas in some container, for ex. ArrayList or HashMap. I want to change that code: public enum OPCODE implements BinaryOperator { MOV((x, y) -> y), INC((x, y) -> ++x), DEC((x, y) -> --x), …
Jump3r
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What's the best way to do a lookup table in C?

I am working on an embedded C project. I have an LCD display and for each character there is a 5x7 dot matrix. To display a specific character you have to shift in 5 bytes that correlate with the dots to turn on. So I need to make some kind of…
PICyourBrain
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Calculate a 32-bit CRC lookup table in C/C++

I want to calculate a 32-bit CRC lookup table. One way I tried is by using the following code from this website: #include #include void make_crc_table() { unsigned long POLYNOMIAL = 0x04c11db7; unsigned long WIDTH = 8…
Programmer_D
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Simple lookup to insert values in an R data frame

This is a seemingly simple R question, but I don't see an exact answer here. I have a data frame (alldata) that looks like this: Case zip market 1 44485 NA 2 44488 NA 3 43210 NA There are over 3.5 million…
Dino Fire
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Country, State, Province WebService?

Are there any good webservices out there that provide good lookup information for Countries and States/Provinces? If so what ones do you use?
Smallinov
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Small Tables in Python?

Let's say I don't have more than one or two dozen objects with different properties, such as the following: UID, Name, Value, Color, Type, Location I want to be able to call up all objects with Location = "Boston", or Type = "Primary". Classic…
akoumjian
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How to use LUT with JavaScript?

I'm new to image processing. I want to use JavaScript to apply effects to images using LUTs (LookUp Tables) or the corresponding lookup PNGs, something like this: I have googled a lot and couldn't find an article or any resource which will describe…
Karlen Kishmiryan
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Cosine lookup table with c++

Here's a snippet that should generate a cosine lookup table of 2048 elements, taken from the book Building Embedded Systems by Changyi Gu: #include #include template constexpr T look_up_table_elem (int i) { return…
xtrinch
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algorithm behind the generation of the reverse bits lookup table(8 bit)

I found the lookup table here. The table is generated as a reverse bits table of 8 bits. I can not figure out why it works. Please explain the theory behind it. Thanks static const unsigned char BitReverseTable256[256] = { # define R2(n) n,…
louxiu
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