All Questions

1
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When should I use mipmaps?

After Google started adding Mipmaps I did not exactly search for why. Even with this addition, it does not prevent anything from using Drawable as it was before. Before res/ drawable-mdpi/ic_launcher.png (48x48 pixels) drawable-...
asked on 22.09.2016 / 20:58
1
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Type Object in PHP

I'm practicing some code in PHP when I come across this: <?php $a = (object) ["a" => "b"]; $b = (object) ["a" => "c"]; $y = $a <=> $b; echo $y; $v=[1,2,3] <=> [1,2,3]; echo $v; $a= (object) ["a" => "b"]; $b = (object)...
asked on 14.11.2018 / 22:26
1
answer

How to delete list elements through a condition?

I used the following function: splitfile<-split(training,list(training$group1,training$city)) and this returns me a list of dataframes with different rows, based on the variables I selected. However, a dataframe with 0 rows is returne...
asked on 02.11.2018 / 15:05
2
answers

Difference between local variable VS global variable

In my micro controller classes the variables are always defined globally and very rarely locally and I would like to know why, because in my head it makes a difference between being global or local. 1. 2. Both the local variable an...
asked on 28.09.2018 / 16:49
1
answer

Why is it possible to store a string in a char pointer?

Why does char store a single character and the pointer points to its value in memory, so should it not have only one character? Example: char *str = "Ola"; Why str does not store just one character?     
asked on 17.11.2018 / 17:55
1
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How to remove the rows based on the values of another variable?

Consider the dataframe: data<-data.frame(a=c(1,3,4,5,6,NA,6,NA),b=c(1,NA,NA,4,6,7,NA,1)) I want to delete the entire line when NA exists in variable 'a' . So, what I hope is: data a b 1 1 1 2 3 NA 3 4 NA 4 5 4 5 6 6 6 6 N...
asked on 05.10.2018 / 18:16
3
answers

What kind of return from a select count (*) in Spring JPA?

I need to know the type of return that Spring JPA returns to put in the Service package, because it is giving NullPointerException : Dao: public interface PlaylistDao extends JpaRepository<Playlist, Long> { @Query("select co...
asked on 23.11.2018 / 18:47
1
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Calculate cubic root

I'm having trouble creating the following Cube root and LN buttons. I have buttons that should be very similar like for example the normal square root and the log. I tried to create the following for the cube root: private void btn_raizc...
asked on 25.09.2016 / 20:08
1
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Calibration of stereo camera through the chessboard in openCV

I'm trying to calibrate a stereo camera using openCV, but the findChessboardCorners function is always returning False, I believe it's due to the high distortion of the image. Any suggestions for preprocessing to make the function accurate? C...
asked on 06.11.2018 / 18:22
1
answer

How to paint multiple page elements by clicking and dragging the mouse?

Essentially my program creates a "screen" of "pixels" where the divs are the pixels. It randomly generates the colors in the image and the user can use a palette that is underneath to change, as if it were to paint. However, I have a dilem...
asked on 26.10.2018 / 21:03