Code to calculate 1D Median Filter

Question

I wonder if anyone knows some python or java code to calculate 1D median filter. I have a file comma delimited with two fields: Date and Signal. Something like that:

2014-06-01 11:22:12, 23.8

2014-06-01 11:23:12, 25.9

2014-06-01 11:24:12, 45.7

I would like to read this file and apply the 1D Median Filter with size 23 for the field Signal and save it in another file to remove the noise.

Thanks in advance.

Alexandre.

Answer 1

In case someone stumbled on this later.

To extract the data you can use regex, while for the custom median filter you can have a look here. I will leave a copy down here in case it is removed:

def medfilt (x, k):
    """Apply a length-k median filter to a 1D array x.
    Boundaries are extended by repeating endpoints.
    """
    assert k % 2 == 1, "Median filter length must be odd."
    assert x.ndim == 1, "Input must be one-dimensional."
    k2 = (k - 1) // 2
    y = np.zeros ((len (x), k), dtype=x.dtype)
    y[:,k2] = x
    for i in range (k2):
        j = k2 - i
        y[j:,i] = x[:-j]
        y[:j,i] = x[0]
        y[:-j,-(i+1)] = x[j:]
        y[-j:,-(i+1)] = x[-1]
    return np.median (y, axis=1)