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Search found 441 results on 18 pages for 'nearest neighbor'.

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• Android drawCircle's are not always 360 degrees

  - by user329999

  When I call drawCircle (ex. canvas.drawCircle(x, y, r, mPaint);) and I use Paint Style STROKE to initialize param #4 mPaint, the result doesn't quite make a full 360 degree (2*PI radian) circle in all cases. Sometimes you get a full circle (as I would expect) and sometimes only an arc. Does someone have an idea what would cause this to happen? I don't know what cases work and which don't (yet). I've noticed the ones that don't work seem to be the larger circles I'm drawing (100.0 radius). Could be size related. I am using floating point for x, y and r. I could try rounding to the nearest int when in the drawing code.

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• How to Get Current Weather via Web Services

  - by Brandon

  I am attempting to get the current weather given a zip code or a set of latitude/longitude coordinates. It appears that best practice to do this (and how NOAA does it) is to get the XML feed for a weather station. Example: http://www.weather.gov/xml/current_obs/KEDW.xml The only problem is that NOAA doesn't provide a good way to find the closest weather station given a zip code or coordinates and I did not see any hosted web services out there that will provide this mapping. Does anyone know of any web services to get the nearest weather station given a zip code or coordinate input? If not, does anyone have any great solutions to look into that provide similar information as NOAA does but takes in a zip code or coordinates?

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• PHP correct indentation?

  - by brainle55

  I'm a beginner PHP coder, recently I've been told I indent my code not correctly. They say this is wrong: if($something) { do_something(); } else { something_more(); and_more(); } While this is right? if($something) { do_something(); } else { something_more(); and_more(); } Really? I am willing to become opensource coder in nearest future so that's why I'm asking how to write code in a good way.

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• Is it possible to find the KNN for a node that is *IN* the KD-tree?

  - by Stephen

  Hi there, Trying to create a KNN search using a KD-tree. I can form the KD-tree fine (or at least, I believe I can!). My problem is that I am searching to find the closest 2 neighbours to every point in a list of points. So, is there a method to find the K nearest neighbours to a point using a KD tree even if the point is actually IN the tree, or do I need to construct a seperate KD tree for each point, leaving out the point that I wish to search for? My implementation language is C++, but I am more looking for either an algorithm or general help, thanks! Thanks, Stephen

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• AttributeError while adding colorbar in matplotlib

  - by bgbg

  The following code fails to run on Python 2.5.4: from matplotlib import pylab as pl import numpy as np data = np.random.rand(6,6) fig = pl.figure(1) fig.clf() ax = fig.add_subplot(1,1,1) ax.imshow(data, interpolation='nearest', vmin=0.5, vmax=0.99) pl.colorbar() pl.show() The error message is C:\temp>python z.py Traceback (most recent call last): File "z.py", line 10, in <module> pl.colorbar() File "C:\Python25\lib\site-packages\matplotlib\pyplot.py", line 1369, in colorbar ret = gcf().colorbar(mappable, cax = cax, ax=ax, **kw) File "C:\Python25\lib\site-packages\matplotlib\figure.py", line 1046, in colorbar cb = cbar.Colorbar(cax, mappable, **kw) File "C:\Python25\lib\site-packages\matplotlib\colorbar.py", line 622, in __init__ mappable.autoscale_None() # Ensure mappable.norm.vmin, vmax AttributeError: 'NoneType' object has no attribute 'autoscale_None' How can I add colorbar to this code? Following is the interpreter information: Python 2.5.4 (r254:67916, Dec 23 2008, 15:10:54) [MSC v.1310 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information. >>>

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• Are tile overlays possible with the iPhone's MapKit

  - by rickharrison

  I already have a tile source set up for use with the Google Maps JavaScript API. I am trying to translate this for use with the iPhone MapKit. I have correctly implemented the javascript zooming levels into mapkit. Whenever - (void)mapView:(MKMapView *)mapView regionDidChangeAnimated:(BOOL)animated is called, I snap the region to the nearest zoom level based on the same center point. Is it possible to implement a solution possibly with CATiledLayer to implement a tiling solution. Does the iPhone use the standard 256x256 tiles like google maps does natively? Any direction or help on this would be greatly appreciated. I would rather not waste a couple weeks trying to implement this if it's not possible.

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• UIPickerView selectedRowInComponent: returns stale data after code adjusts it

  - by Eric Lloyd

  I have a UIPickerView with multiple components. Some values are grayed out, and my pickerView:didSelectRow:inComponent honors this by shifting the picker component in question to the nearest valid value, much as UIDatePicker moves from "30" to "28" when you select "February". Then it calls a delegate method to announce the adjusted value. When my adjuster method calls my UIPickerView's selectRow:inComponent:animated:YES, the value on screen is correct, but the values from selectedRowInComponent: are stale (from before the adjustment for gray values). However, if I call selectRow:inComponent:animated:NO, the returned values are correct, but the lack of animation is jarring. I've tried wrapping the adjustment in a beginAnimations:/commitAnimations block and catching the values in UIView's +animationDidStopSelector, but I still get stale values. Has anyone run into this before?

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• OpenGL billboard interpolation issue

  - by PeanutPower

  I have a billboard quad with a texture mapped onto it. This is basically some text with transparency. The billboard floats forwards and backwards from the camera's perspective. As the billboard moves away (and appears smaller) there is an flickering effect around the edges of the text where there is a stroke border on the actual texture. I think this is because interpolation is needed as the image which is normally X pixels wide is now shown as only a % of X and some pixels need to be merged together. I guess it's doing nearest neighbour or something? Can anyone point me in the right direction for opengl settings to control this, I'm guessing there is some way of preventing this effect from happening by adjusting the method for how the texture is handled ?

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• How is joystick axis information formatted from a USB Joystick?

  - by aquanar

  I actually just have a rather small question, but I have had the HARDEST time finding information about it. For the application I am programming for, there will be a 3-axis joystick being connected via USB to a Windows XP computer, and it is being handled by directx. That information will then be sent elsewhere to an embedded controller. I don't need to know too much of the intricacies of how directx handles it, but I want to know, how is the data for the axes formatted? Nearest I can tell, most joysticks nowadays have 12 bits of resolution, so is the data output as a 12-bit 2's compliment number? And after that, is it represented as a signed 16-bit integer when it is captured from directx? I'd like to know this so I know how I will work with the data at the embedded platform side, such as how to format the packets sending data to the embedded side, as well ashow to use the information once it is on the embedded side.

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• Confusion Matrix with number of classified/misclassified instances on it (Python/Matplotlib)

  - by Pinkie

  I am plotting a confusion matrix with matplotlib with the following code: from numpy import * import matplotlib.pyplot as plt from pylab import * conf_arr = [[33,2,0,0,0,0,0,0,0,1,3], [3,31,0,0,0,0,0,0,0,0,0], [0,4,41,0,0,0,0,0,0,0,1], [0,1,0,30,0,6,0,0,0,0,1], [0,0,0,0,38,10,0,0,0,0,0], [0,0,0,3,1,39,0,0,0,0,4], [0,2,2,0,4,1,31,0,0,0,2], [0,1,0,0,0,0,0,36,0,2,0], [0,0,0,0,0,0,1,5,37,5,1], [3,0,0,0,0,0,0,0,0,39,0], [0,0,0,0,0,0,0,0,0,0,38] ] norm_conf = [] for i in conf_arr: a = 0 tmp_arr = [] a = sum(i,0) for j in i: tmp_arr.append(float(j)/float(a)) norm_conf.append(tmp_arr) plt.clf() fig = plt.figure() ax = fig.add_subplot(111) res = ax.imshow(array(norm_conf), cmap=cm.jet, interpolation='nearest') cb = fig.colorbar(res) savefig("confmat.png", format="png") But I want to the confusion matrix to show the numbers on it like this graphic (the right one): http://i48.tinypic.com/2e30kup.jpg How can I plot the conf_arr on the graphic?

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• Create method to handle multiple types of controls

  - by Praesagus

  I am trying to create a method that accepts multiple types of controls - in this case Labels and Panels. The conversion does not work because IConvertible doesn't convert these Types. Any help would be so appreciated. Thanks in advance public void LocationsLink<C>(C control) { if (control != null) { WebControl ctl = (WebControl)Convert.ChangeType(control, typeof(WebControl)); Literal txt = new Literal(); HyperLink lnk = new HyperLink(); txt.Text = "If you prefer a map to the nearest facility please "; lnk.Text = "click here"; lnk.NavigateUrl = "/content/Locations.aspx"; ctl.Controls.Add(txt); ctl.Controls.Add(lnk); } }

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• More specific NSNumberFormatter failure behaviour

  - by Volte

  I have an NSTextField into which I need the user to enter a number between a max and min, and it would be nice if I could detect when the NSNumberFormatter fails that particular test so I can either display a nicer message ("The number is too large" is not very helpful, it needs to display the valid range) or simply set the field automatically to the nearest valid value. I've looked at the NSTextField delegate's -control:didFailToFormatString:errorDescription: method which doesn't seem to allow you to modify the error, and I've looked at overriding the NSNumberFormatter's -getObjectValue:forString:range:error: method which does give me an NSError that I can modify, but there doesn't seem to be any way to determine which specific error was returned. Since I am just entering a simple integer, I don't need most of the functionality in NSNumberFormatter, would I be better off just writing my own formatter from scratch?

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• How to get nearby POIs

  - by balexandre

  I have a database with Points of Interest that all have an address. I want to know what is the method/name/call to get all nearby POIs from a given position. I understand that I need to convert all my addresses to LAT / LON coordinates at least, but my question is: for a given LAT / LONG how do I get from the database/array what POIs are nearby by distance, for example: You are here 0,0 nearest POIs in a 2km radius are: POI A (at 1.1 Km) POI C (at 1.3 Km) POI F (at 1.9 Km) I have no idea what should I look into to get what I want :-( Any help is greatly appreciated. Thank you

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• Find top "n" nearby coordinates.

  - by John Hamelink

  I have a coordinate. I want to find the top "n" (n being a variable value) nearest coordinates out of several thousand rows stored on a MySQL database. I also want to be able to define maximum and minimum distances between the coordinate in question and the coordinates in the database. How best am I to go about this? Would it be bonkers to use PHP as I understand the syntax much better than MySQL? If I use a MySQL function, how do I move it between databases if I choose to switch servers? How is it stored? Lastly, what is the most efficient method of getting through all these coordinates accurately - the coordinates are all relatively close to one another? Thanks for your time, John.

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• Specification, modeling and programming are principially the same, right?

  - by Gabriel Šcerbák

  In formal specifications based on abstract algebraic types and equational theory you use formulas of equational theory to specify theory. System which will satisfy those constraints is called in formal logic a model. Modeling is process of creating a model, which abstracts of some aspects, which are unnecessary details for a specific case. So concrete system has to adhere to created model in observed aspects. Programming is a process of creating a program which will have specific behaviour - will perform specific algorithms - and programming languages through different paradigms enable us to think in a certain specific way, which abstracts of some details, usually machine specific ones. So could we be doing all those things at the same time, because they are principially the same? Is declarative programming the nearest attempt to do that? Could we use some sort f programming languages which will be good for programming as well as for modeling and specification?

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• iPhone: Turning latitude/longitude into "major cross-streets"

  - by Gloria

  Using the MKReverseGeocoder or GoogleAPI or MapKit... Is there a simple way to turn a latitude/longitude into "nearest major cross-streets"? A user might not have any idea where "12345 Pineapple" is located... so I want to show something like "Pineapple and Main"... or (larger, major roads) like "US-140 and Hwy 76". I don't really care what "major" is defined as... perhaps any road with higher speed limits... or more than 3 lanes... etc. I don't really care what "close by" is defines as... perhaps within 0-10 miles... or just "closest found".

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• Is it safe to catch an access violation in this scenario?

  - by Eloff

  I've read a lot, including here on SO that suggests this is a very bad idea in general and that the only thing you can do safely is exit the program. I'm not sure that this is true. This is for a pooling memory allocator that hands off large allocations to malloc. During pool_free() a pointer needs to be checked it it belongs to a pool or was allocated with malloc. By rounding the address down to the nearest 1MB boundary, I get a pointer to the beginning of a block of memory in the pool, or undefined if malloc was used. In the first case I can easily verify that the block of memory belongs to the pool, but, if it does not I will either fail this verification, or I will get an access violation (note that this is a read-only process). Could I not catch this with SEH (Windows) or handle the signal (POSIX) and simply treat it as a failed verification? (i.e. this is only possible if malloc was used, so pass the ptr to free())

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• Properly trimming PCM data from a ByteArray

  - by Lowgain

  I have a situation where I need to trim a small amount of audio from the beginning of a recorded clip (generally somewhere between 110-150ms, it is an inconsistent amount). I'm recording in 44100 frequency and 16 bitrate. This is the code I'm using: public function get trimmedData():ByteArray { var ba:ByteArray = new ByteArray(); var bitPosition:uint = 44100 * 16 * (recordGap / 1000); bitPosition -= int(bitPosition % 16); //should keep snapped to nearest sample, I hope ba.writeBytes(_rawData, (bitPosition / 8)); return ba; } This seems to work time-wise, but all the recorded audio gets staticy and gross. Is something off about my rounding? This is the first time I've needed to alter raw PCM data so I'm not sure about the finer details of it. Thanks!

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• calculate distance with linq or subsonic C# MVC

  - by minus4

  i have this MySQL statement from a search page, the user enters there postcode and it finds the nearest stiocklist within 15 MIles of the entered postcode. SELECT * , ( ( ACOS( SIN( "+SENTLNG +" * PI( ) /180 ) * SIN( s_lat * PI( ) /180 ) + COS( " + SENTLNG +" * PI( ) /180 ) * COS( s_lat * PI( ) /180 ) * COS( ( " + SENTLANG + " - s_lng ) * PI( ) /180 ) ) *180 / PI( ) ) *60 * 1.1515 ) AS distance_miles FROM new_stockists WHERE s_lat IS NOT NULL HAVING distance_miles <15 ORDER BY distance_miles ASC LIMIT 0 , 15 but now i am using linq and subsonic and not got a clue how do do this in linq or subsonic your help would be much appreciated, please also not that i have to sent in a dynamic from address, thats the postcode mentioned at the top of the page, i do a call to google to get then lng and lat from them for the postcode given.

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• What parameters should I use in a Google Maps URL to go to a lat-lon?

  - by xpda

  I would like to produce a url for Google Maps that goes to a specific latitude and longitude. Now, I generate a url such as this: http://maps.google.com/maps?z=11&t=k&q=58 41.881N 152 31.324W The resulting map comes up with a round "A" balloon pointer, which seems to point to the nearest named object, and a green arrow, which points to the lat-lon. Sometimes, as in this example, the "A" pointer is centered and is far enough away that you cannot see the pointer to the lat-lon. (Zoom out to see both pointers in this example. The "A" pointer is in the center of Alaska, while the lat-long pointer is on Kodiak Island.) Are there some parameters I can use in the Google Maps URL that will produce a single pointer to a designated lat-lon? (This loads in a separate window. It is not embedded.)

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• Is this a "valid" css image replacement technique?

  - by user278457

  I just came up with this, it seems to work in all modern browsers, I just tested it then on (IE8/compatibility, Chrome, Safari, Moz) HTML <img id="my_image" alt="my text" src="images/small_transparent.gif" /> CSS #my_image{ background-image:url('images/my_image.png'); width:100px; height:100px;} Pro's: image alt text is best-practice for accessibility/seo no extra HTML markup, and the css is pretty minimal too gets around the css on/images off issue where "text-indent" techniques hide text from low bandwidth users The biggest disadvantage that I can think of is the css off/images on situation, because you'll only send a transparent gif. I'd like to know, who uses images without stylesheets? some kind of mobile phone or something? I'm making some sites for clients in regional Australia (hundreds of km from the nearest city), where many users will be suffering from dial-up connections, and often outdated browsers too, so the "images off" issue is an important consideration. are there any other side effects with this technique that I haven't considered?

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• Find point which sum of distances to set of other points is minimal

  - by Pawel Markowski

  I have one set (X) of points (not very big let's say 1-20 points) and the second (Y), much larger set of points. I need to choose some point from Y which sum of distances to all points from X is minimal. I came up with an idea that I would treat X as a vertices of a polygon and find centroid of this polygon, and then I will choose a point from Y nearest to the centroid. But I'm not sure whether centroid minimizes sum of its distances to the vertices of polygon, so I'm not sure whether this is a good way? Is there any algorithm for solving this problem? Points are defined by geographical coordinates.

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• calculate distance with linq or subsonic

  - by minus4

  i have this MySQL statement from a search page, the user enters there postcode and it finds the nearest stiocklist within 15 MIles of the entered postcode. SELECT * , ( ( ACOS( SIN( "+SENTLNG +" * PI( ) /180 ) * SIN( s_lat * PI( ) /180 ) + COS( " + SENTLNG +" * PI( ) /180 ) * COS( s_lat * PI( ) /180 ) * COS( ( " + SENTLANG + " - s_lng ) * PI( ) /180 ) ) *180 / PI( ) ) *60 * 1.1515 ) AS distance_miles FROM new_stockists WHERE s_lat IS NOT NULL HAVING distance_miles <15 ORDER BY distance_miles ASC LIMIT 0 , 15 but now i am using linq and subsonic and not got a clue how do do this in linq or subsonic your help would be much appreciated, please also not that i have to sent in a dynamic from address, thats the postcode mentioned at the top of the page, i do a call to google to get then lng and lat from them for the postcode given.

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• best method of turning millions of x,y,z positions of particles into visualisation

  - by Griff

  I'm interested in different algorithms people use to visualise millions of particles in a box. I know you can use Cloud-In-Cell, adaptive mesh, Kernel smoothing, nearest grid point methods etc to reduce the load in memory but there is very little documentation on how to do these things online. i.e. I have array with: x,y,z 1,2,3 4,5,6 6,7,8 xi,yi,zi for i = 100 million for example. I don't want a package like Mayavi/Paraview to do it, I want to code this myself then load the decomposed matrix into Mayavi (rather than on-the-fly rendering) My poor 8Gb Macbook explodes if I try and use the particle positions. Any tutorials would be appreciated.

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• Calculating terrain height in 3d-space

  - by Jonas B

  Hi I'm diving into 3d programming a bit and am currently learning by writing a procedural terrain generator that generates terrain based on a heightmap. I would also want to implement some physics and my first attempt at terrain collision was by simply checking the current position vs the heightmap. This however wont work well against small objects as you'd have to calculate the height by taking the heightdifference of the nearest vertices of the object and doing this every colision check is pretty slow. Beleive me I tried googling for it but there's simply so much crap and millions of blogs posting ripped-of newbie tutorials everywhere with basically no real information on the subject, I can't find anything that explains it or even names any generally used techniques. I'm not asking for code or a complete solution, but if anyone knows a particular technique good for calculating a high-res heightmap out of the already generated and smoothed terrain I would be very happy as I could look into it further when I know what I'm looking for. Thanks

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