How to convert pixelmap to a Picture – JAVA

Hi,

As part of the Kaggle Challenge, I have had to visualize training data which is a bunch of numbers with pixel intensity. To convert this into a picture file like jpeg or bmp I needed convertors. I found some JAVA code online but it didn’t solve my problem. I needed to tweak it a bit to make it work for my example.

The input to the program is a pixel map like this;

To convert this into a picture, you can use the below code;

note: My pixel map is of 2304 pixel intensities which translates to 48*48 Pixel image. Hence, the code below works with this. For other dimensions update the pic accordingly;

import java.awt.image.BufferedImage;
import java.awt.image.WritableRaster;
import java.io.File;
import javax.imageio.ImageIO;

public class pixtoImage {

/**
* @param args
*/
public static void main(String[] args) {
// TODO Auto-generated method stub
File imageFile = new File("D:/Pics/0-6.png");
//3 bands in TYPE_INT_RGB
int NUM_BANDS = 3;
int[] pixelMap = new int[48 * 48 * NUM_BANDS];
int band;
for (int i = 0; i < 48; i++)
{
for (int j = 0; j < 48; j++) {
for (band = 0; band < NUM_BANDS; band++){
pixelMap[((i * 48) + j)*NUM_BANDS + band] = Integer.parseInt(args[((i * 48) + j)]);

}
}
}
BufferedImage picImage = getImageFromArray(pixelMap, 48, 48);
try{
ImageIO.write(picImage, "png", imageFile);
}
catch(Exception e){
e.printStackTrace();
};
System.out.println("Written");
}

public static BufferedImage getImageFromArray(int[] pixels, int width, int height)
{
BufferedImage image =
new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
WritableRaster raster = (WritableRaster) image.getData();
raster.setPixels(0, 0, width, height, pixels);
image.setData(raster);
return image;
}
}

Output for the pixel map shown in the image above is

May this snippet save you some time, Have fun…..

Reading humungous csv files in R

Hi,

The other day, for kaggle I had to read a csv file into R. It was around 4GB in size. None of the text editors were able to open the file. Even Access text import failed. I had to work with a macro or had to look at open source RDBMS like MySql. Luckily, my teammate gave me the idea of using file stream reader and writers in Java, Also my manager showed me this link.

I didn’t need to read the entire file, for initial experiments I needed only a part of the file. So, the below is a code snippet to get a part of the csv;

# initializing file readers
x<-file('extra_unsupervised_data.csv','rt')
x
y<-file('unsupervised_trim.csv','wt')
y

# reading lines
line<-readLines(x,n=10001)

# writing lines
cat(line,file='unsupervised_trim.csv',fill=TRUE)

# closing files
close(x)
close(y)

May this snippet save you some time!!!!!