how to plot tfr topomap of epochs in local area like the attribute 'extrapolate' in evoked_plot _topomap

You can plot values from raw numpy arrays with mne.viz.plot_topomap. So first you can get spectral power in a numpy array and then plot the desired frequency in this way:

psd, freq = mne.time_frequency.psd_welch(epochs)
# the psd array has shape epochs x channels x frequencies, so we average
# the epochs dimension
psd_average = psd.mean(axis=0)

# lets say we want to plot 10 Hz
plot_freq = 10
# we find the index of this frequency
freq_idx = (np.abs(freq - plot_freq)).argmin()
# we plot the topography of power for the chosen frequency
mne.viz.plot_topomap(psd_average[:, freq_idx], epochs.info)
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