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• How to notice unusual news activity

  - by ??iu

  Suppose you were able keep track of the news mentions of different entities, like say "Steve Jobs" and "Steve Ballmer". What are ways that could you tell whether the amount of mentions per entity per a given time period was unusual relative to their normal degree of frequency of appearance? I imagine that for a more popular person like Steve Jobs an increase of like 50% might be unusual (an increase of 1000 to 1500), while for a relatively unknown CEO an increase of 1000% for a given day could be possible (an increase of 2 to 200). If you didn't have a way of scaling that your unusualness index could be dominated by unheard-ofs getting their 15 minutes of fame.

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• help with matlab and Discrete Fourier transform

  - by user504363

  Hi all I have previous experience with Matlab, but the problem that I face some problems in apply a problem in (DSP : Digital signal processing) which is not my study field, but I must finish that problems in days to complete my project. all i want is help me with method and steps of solving this problem in matlab and then I can write the code with myself. the problem is about the signal x(t) = exp(-a*t); 1) what's the Discrete Fourier transform of the sampled signal with sample rate fs 2) if a=1 and fs =1 , plot the amplitude spectrum of sampled signal 3) fix the sampling frequency at fs = 1(hz) [what's it mean ?] and plot the magnitude of the Fourier Transform of the sampled signal at various values of a thanks

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• Is SELECT INTO able to affect data from its original table during UPDATE

  - by driveby

  Whilst asking this question asp.net scheduling timed events user murph posted some insightful information: Point about this is that its very, very simple - you have an process for exchange that is performing a clearly defined task and you have a high frequency task that is not doing anything particularly complex, its a straightforward query (select from table where sent = false and send at < value) - probably into temporary table so that you can run a single query update after you've done the sends - that you can optimise the index for. You're not trying to queue up a huge pile of event triggers, just one that fires once a minute and processes things that are due. Is it possible to SELECT data from table X INTO table Y and have the UPDATES that are performed on table Y pushed into table X? I guess the alternative would be that the data gets updated in table Y then an update command can be run on table X based on the data in table Y. What would be the advantage of selecting into another table? Thank you,

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• How to calculate a operation's time in micro second precision

  - by Sanjeet Daga

  I want to calculate performance of a function in micro second precision on Windows platform. Now Windows itself has milisecond granuality, so how can I achieve this. I tried following sample, but not getting correct results. LARGE_INTEGER ticksPerSecond = {0}; LARGE_INTEGER tick_1 = {0}; LARGE_INTEGER tick_2 = {0}; double uSec = 1000000; // Get the frequency QueryPerformanceFrequency(&ticksPerSecond); //Calculate per uSec freq double uFreq = ticksPerSecond.QuadPart/uSec; // Get counter b4 start of op QueryPerformanceCounter(&tick_1); // The ope itself Sleep(10); // Get counter after opfinished QueryPerformanceCounter(&tick_2); // And now the op time in uSec double diff = (tick_2.QuadPart/uFreq) - (tick_1.QuadPart/uFreq);

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• C typedef struct uncertainty.

  - by Emanuel Ey

  Consider the following typedef struct in C: 21:typedef struct source{ 22: double ds; //ray step 23: double rx,zx; //source coords 24: double rbox1, rbox2; //the box that limits the range of the rays 25: double freqx; //source frequency 26: int64_t nThetas; //number of launching angles 27: double theta1, thetaN; //first and last launching angle 28:}source_t; I get the error: globals.h:21: error: redefinition of 'struct source' globals.h:28: error: conflicting types for 'source_t' globals.h:28: note: previous declaration of 'source_t' was here I've tried using other formats for this definition: struct source{ ... }; typedef struct source source_t; and typedef struct{ ... }source_t; Which both return the same error. Why does this happen? it looks perfectly right to me.

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• SOLR and Natural Language Parsing - Can I use it?

  - by andy

  hey guys, my requirements are pretty similar to this: Requirements http://stackoverflow.com/questions/90580/word-frequency-algorithm-for-natural-language-processing Using Solr While the answer for that question is excellent, I was wondering if I could make use of all the time I spent getting to know SOLR for my NLP. I thought of SOLR because: It's got a bunch of tokenizers and performs a lot of NLP. It's pretty use to use out of the box. It's restful distributed app, so it's easy to hook up I've spent some time with it, so using could save me time. Can I use Solr? Although the above reasons are good, I don't know SOLR THAT well, so I need to know if it would be appropriate for my requirements. Ideal Usage Ideally, I'd like to configure SOLR, and then be able to send SOLR some text, and retrieve the indexed tonkenized content. Context So you guys know, I'm working on a small component of a bigger recommendation engine.

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• How to extract comment out of header file using python, perl, or sed?

  - by WilliamKF

  I have a header file like this: /* * APP 180-2 ALG-254/258/772 implementation * Last update: 03/01/2006 * Issue date: 08/22/2004 * * Copyright (C) 2006 Somebody's Name here * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the project nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. */ #ifndef HEADER_H #define HEADER_H /* More comments and C++ code here. */ #endif /* End of file. */ And I wish to extract out the contents of the first C style comment only and drop the " *" at the start of each line to get a file with the following contents: APP 180-2 ALG-254/258/772 implementation Last update: 03/01/2006 Issue date: 08/22/2004 Copyright (C) 2006 Somebody's Name here All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution. 3. Neither the name of the project nor the names of its contributors may be used to endorse or promote products derived from this software without specific prior written permission. THIS SOFTWARE IS PROVIDED BY THE PROJECT AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE PROJECT OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Please suggest an easy way to do this with Python, Perl, sed, or some other way on Unix. Preferably as a one-liner.

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• MySQL Many to Many with Unique keys and Update/Select if Exists otherwise Insert

  - by Jayrox

  In my goal to have a Many-to-Many relationship in my MySQL database I have arrived at another bridge to build. Current Tables: Users (id, name) Tags (id, name) User_Tags (user_id, tag_id) Here is the goal: I would like to have the ability to take a tag i.e: #fb and insert it into my Tags database which has a unique constraint on name and if the tag exists I would like to return it's id I would like to insert the tag.id and the current user's user.id into User_Tags. I do not have any unique constraints on the User_Tags table because I would like to be able to track the user's most commonly used tags and present them in a list ordered by frequency of use. I am currently developing this project in PHP using prepared statements. Additionally, performance is not currently an issue as my user count is still fairly small, but it is steadily growing and may be an issue in the future.

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• Does it make a difference in performance if I use self.fooBar instead of fooBar?

  - by mystify

  Note: I know exactly what a property is. This question is about performance. Using self.fooBar for READ access seems a waste of time for me. Unnecessary Objective-C messaging is going on. The getters typically simply pass along the ivar, so as long as it's pretty sure there will be no reasonable getter method written, I think it's perfectly fine to bypass this heavy guy. Objective-C messaging is about 20 times slower than direct calls. So if there is some high-performance-high-frequency code with hundreds of properties in use, maybe it does help a lot to avoid unnessessary objective-c messaging? Or am I wasting my time thinking about this?

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• How can I load an MP3 or similar music file for display and analysis in wxWidgets?

  - by Jon Cage

  I'm developing a GUI in wxPython which allows a user to generate sequences of colours for some toys I'm building. Part of the program needs to load an MP3 (and potentially other formats further down the line) and display it to the user. That should be sufficient to get started but later I'd like to add features like identifying beats and some crude frequency analysis. Is there any simple way of loading / understanding an MP3's contents to display a plot of its amplitudes to the screen using wxWidgets? I later intend to port to C++/wxWidgets for speed and to avoid having to distribute wxPython.

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• Invalid ADTS sampling_frequency_index and channel_configuration why?

  - by Moto

  Hello all, I hope someone can direct me on the right path before I put a lot of time and effort on this. I'm currently trying to parse an AAC+ frame to get information such as number of channels and sample frequency. So it seems that we can simply get this information from the ADTS header but most of the time this information is inaccurate. So the question is: -Why is this data inaccurate? What is the meaning of the ADTS header channel and sample freq? Should I rely on it? -Should I parse further down the frame to get this information? FYI, the AAC+ raw data is coming from streaming servers... Thanks for the help! -Moto

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• Plotting a cumulative graph of python datetimes

  - by ventolin

  Say I have a list of datetimes, and we know each datetime to be the recorded time of an event happening. Is it possible in matplotlib to graph the frequency of this event occuring over time, showing this data in a cumulative graph (so that each point is greater or equal to all of the points that went before it), without preprocessing this list? (e.g. passing datetime objects directly to some wonderful matplotlib function) Or do I need to turn this list of datetimes into a list of dictionary items, such as: {"year": 1998, "month": 12, "date": 15, "events": 92} and then generate a graph from this list? Sorry if this seems like a silly question - I'm not all too familiar with matplotlib, and would like to save myself the effort of doing this the latter way if matplotlib can already deal with datetime objects itself.

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• Excel - Counting unique values that meet multiple criteria

  - by wotaskd

  I'm trying to use a function to count the number of unique cells in a spreadsheet that, at the same time, meet multiple criteria. Given the following example: A B C QUANT STORE# PRODUCT 1 75012 banana 5 orange 6 56089 orange 3 89247 orange 7 45321 orange 2 apple 4 45321 apple In the example above, I need to know how many unique stores with a valid STORE# have received oranges OR apples. In the case above, the result should be 3 (stores 56089, 89247 and 45321). This is how I started to try solving the problem: =SUM(IF(FREQUENCY(B2:B9,B2:B9)>0,1)) The above formula will yield the number of unique stores with a valid store#, but not just the ones that have received oranges or bananas. How can I add that extra criteria?

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• data structure for counting frequencies in a database table-like format

  - by user373312

  i was wondering if there is a data structure optimized to count frequencies against data that is stored in a database table-like format. for example, the data comes in a (comma) delimited format below. col1, col2, col3 x, a, green x, b, blue ... y, c, green now i simply want to count the frequency of col1=x or col1=x and col2=green. i have been storing the data in a database table, but in my profiling and from empirical observation, database connection is the bottle-neck. i have tried using in-memory database solutions too, and that works quite well; the only problem is memory requirements and quirky init/destroy calls. also, i work mainly with java, but have experience with .net, and was wondering if there was any api to work with "tabular" data in a linq way using java. any help is appreciated.

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• How to quantify your "slow" development machine?

  - by lance

  ( Please provide the question this one duplicates. I'm disappointed I couldn't find it. ) My development machine is "slow". I wait on it "a lot". I've been asked by decision makers who want to help to fairly and accurately measure that time. How do you quantify the amount of time you spend waiting on the computer (during compiles, waiting for apps to open every day, etc). Is there software which effectively reports on this sort of thing? Is there an OS metric (I/O something something, pagefile swapping frequency, etc, etc) that captures and communicates this particularly well? Some sort of benchmark you'd recommend me testing against?

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• Microphone input

  - by George

  I'm trying to build a gadget that detects pistol shots using Android. It's a part of a training aid for pistol shooters that tells how the shots are distributed in time and I use a HTC Tattoo for testing. I use the MediaRecorder and its getMaxAmplitude method to get the highest amplitude during the last 1/100 s but it does not work as expected; speech gives me values from getMaxAmplitude in the range from 0 to about 25000 while the pistol shots (or shouting!) only reaches about 15000. With a sampling frequency of 8kHz there should be some samples with considerably high level. Anyone who knows how these things work? Are there filters that are applied before registering the max amplitude. If so, is it hardware or software? Thanks, /George

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• "Winamp style" spectrum analyzer

  - by cvb

  I have a program that plots the spectrum analysis (Amp/Freq) of a signal, which is preety much the DFT converted to polar. However, this is not exactly the sort of graph that, say, winamp (right at the top-left corner), or effectively any other audio software plots. I am not really sure what is this sort of graph called (if it has a distinct name at all), so I am not sure what to look for. I am preety positive about the frequency axis being base two exponential, the amplitude axis puzzles me though. Any pointers?

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• [WiX] Is there a way to create a patch that is identical to doing a full install of the newer versio

  - by Davy8

  I'm trying to create patches using the method from this tutorial. An issue I'm running into is that I can't install a new patch on top of a previous patch. I can full install Version A,then patch to Version B. After that I can't patch to Version C. I can full install Version B, then patch to Version C. Currently we just do full installs with major updates each time which is working fine, but because of the frequency of our (internal) updates the file size and update time is becoming a burden so we're looking to reduce the update time (both downloading and installing) especially when most of the files don't change.

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• Advanced text search in actionscript-return ALL nouns,adjectives and verbs..

  - by eco_bach

  Hi I know that as3 has some powerful new text search capabilities, especially when combined with regex. I don't even know if this is possible, but I would like to somehow, search any block of text, and return all nouns, adjectives and verbs. What would be the best(most efficent) way to do this? Is regex an option? or would I have to load in some sort of open sourced dictionary 9as used in spellcheckers) to compare with or?? After, I've pulled all the nouns, adjectives and verbs, I need to count and prioritize by their frequency. Any suggestions welcome...

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• Ruby on Rails - observe_field help

  - by miligraf

  Trying to put in field "pagar" the calculated value of "precio" * 15% but I don't know why it is not working :S <% form_for @libro, :html => { :multipart => true } do |f| %> <%= f.label "Precio (si es venta):" %> <%= f.text_field :precio %> <%= observe_field :libro_precio, :frequency => 0.25, :update => :libro_pagar, :with => 'value*0.15' %> <%= f.label "A pagar (si es venta):" %> <%= f.text_field :pagar %> <% end %>

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• android spectrum analysis of streaming input

  - by TheBeeKeeper

  for a school project I am trying to make an android application that, once started, will perform a spectrum analysis of live audio received from the microphone or a bluetooth headset. I know I should be using FFT, and have been looking at moonblink's open source audio analyzer ( http://code.google.com/p/moonblink/wiki/Audalyzer ) but am not familiar with android development, and his code is turning out to be too difficult for me to work with. So I suppose my questions are, are there any easier java based, or open source android apps that do spectrum analysis I can reference? Or is there any helpful information that can be given, such as; steps that need be taken to get the microphone input, put it into an fft algorithm, then display a graph of frequency and pitch over time from its output? Any help would be appreciated, thanks.

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• Microphone input

  - by George

  I'm trying to build a gadget that detects pistol shots using Android. It's a part of a training aid for pistol shooters that tells how the shots are distributed in time and I use a HTC Tattoo for testing. I use the MediaRecorder and its getMaxAmplitude method to get the highest amplitude during the last 1/100 s but it does not work as expected; speech gives me values from getMaxAmplitude in the range from 0 to about 25000 while the pistol shots (or shouting!) only reaches about 15000. With a sampling frequency of 8kHz there should be some samples with considerably high level. Anyone who knows how these things work? Are there filters that are applied before registering the max amplitude. If so, is it hardware or software? Thanks, /George

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• How can I load an MP3 or similar music file for display and anaysis in wxWdigets?

  - by Jon Cage

  I'm developing a GUI in wxPython which allows a user to generate sequences of colours for some toys I'm building. Part of the program needs to load an MP3 (and potentially other formats further down the line) and display it to the user. That shuold be sufficient to get started but later I'd like to add features like identifying beats and some crude frequency analysis. Is there any simple way of loading / understanding an MP3's contents to display a plot of it's amplitudes to the screen using wxWidgets? I later intend to port to C++/wxWidgets for speed and to avoid having to distribute wxPython.

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• Filtering spectrum using FIR filters

  - by Alex Hoppus

  If i have signal values x[T] and filter coefficients b[i], i can perform filtering using convolution. Suppose i have spectrum of x (after FFT) and i need to perform filtering using filters coefficients, how can i perform this? I heard that in frequency domain it will be multiplying, rather than convolution (time domain). But i can't find an equation to use it. I have 614000 values in y = fft(x[T]) vector and 119 filter coefficients (generated using fdatool), i can't multiply them directly ... Thanks.

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• Why this friend function can't access a private member of the class?

  - by Alceu Costa

  I am getting the following error when I try to access bins private member of the GHistogram class from within the extractHistogram() implementation: error: 'QVector<double> MyNamespace::GHistogram::bins' is private error: within this context Where the 'within this context' error points to the extractHistogram() implementation. Does anyone knows what's wrong with my friend function declaration? Here's the code: namespace MyNamespace{ class GHistogram { public: GHistogram(qint32 numberOfBins); qint32 getNumberOfBins(); /** * Returns the frequency of the value i. */ double getValueAt(qint32 i); friend GHistogram * Gbdi::extractHistogram(GImage *image, qint32 numberOfBins); private: QVector<double> bins; }; GHistogram * extractHistogram(GImage * image, qint32 numberOfBins); }

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