Tapers

This example shows how to create some basic tapers in 1d, 2d, and 3d using the pylops.utils.tapers module.

import matplotlib.pyplot as plt

import pylops

plt.close("all")

Let’s first define the time and space axes

par = {
    "ox": -200,
    "dx": 2,
    "nx": 201,
    "oy": -100,
    "dy": 2,
    "ny": 101,
    "ot": 0,
    "dt": 0.004,
    "nt": 501,
    "ntapx": 21,
    "ntapy": 31,
}

We can now create tapers in 1d

tap_han = pylops.utils.tapers.hanningtaper(par["nx"], par["ntapx"])
tap_cos = pylops.utils.tapers.cosinetaper(par["nx"], par["ntapx"], False)
tap_cos2 = pylops.utils.tapers.cosinetaper(par["nx"], par["ntapx"], True)

plt.figure()
plt.plot(tap_han, "r", label="hanning")
plt.plot(tap_cos, "k", label="cosine")
plt.plot(tap_cos2, "b", label="cosine square")
plt.title("Tapers")
plt.legend()

Out:

<matplotlib.legend.Legend object at 0x7f770c532240>

Similarly we can create 2d and 3d tapers with any of the tapers above

tap2d = pylops.utils.tapers.taper2d(par["nt"], par["nx"], par["ntapx"])

plt.figure(figsize=(7, 3))
plt.plot(tap2d[:, par["nt"] // 2], "k", lw=2)
plt.title("Taper")

tap3d = pylops.utils.tapers.taper3d(
    par["nt"], (par["ny"], par["nx"]), (par["ntapy"], par["ntapx"])
)

plt.figure(figsize=(7, 3))
plt.imshow(tap3d[:, :, par["nt"] // 2], "jet")
plt.title("Taper in y-x slice")
plt.xlabel("x")
plt.ylabel("y")

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Out:

Text(87.24078657865785, 0.5, 'y')