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I have an array [x,y] where the values of x is ascending and the y values are random. I would like to sum all of the y values together when the x values are within a certain range. I can't show you any code as i dont even know where to start with this but this is the desired effect:-

Example data:-

(1, 0.5)

(2, 5.0)

(4, 2.0)

(7, 0.5)

(8, 0.5)

(10, 2.5)

(11, 1.5)

(15, 3.0)

(18, 4.0)

(20, 0.5)

...... etc.

If the range of y is 10. So from y=1 to y=10 and from y=11 to y=20 the x values will be summed within these two bands, I will get a list:-

11.0, 9.0, ...... etc.

So far I have been advised to sum all the y values, this gives:-

```
import numpy, scipy, matplotlib.pylab as plt
mjd1, flux1, error1 = numpy.loadtxt("log_207_band1.dat", usecols=(1,2,3), unpack=True)
x=mjd1
y=flux1
z=zip(x,y)
print sum(i[1] for i in z)
```

I'm really at a loss of what to do next.

Thanks.