When using raw.plot(), the image is wrong when the set ch_types

[spbgzh (guozihan)]

• MNE version: MNE 1.2.1
• operating system: macOS 12
• Data Set : Seed-IV

import mne
import scipy.io as scio
data_path = “./eeg_raw_data/eeg_raw_data/1/1_20160518.mat”

file_name = “cz_eeg1”
raw_data = scio.loadmat(data_path)
index_list = [0, 2, 25, 29, 41, 49, 58, 60, 5, 13, 7, 11, 23, 31, 43, 47]
data = list(map(lambda i: raw_data[file_name][i], index_list))
ch_names = [“Fp1”,“Fp2”,“C3”,“C4”,“P7”,“P8”,“O1”,“O2”,“F7”,“F8”,“F3”,“F4”,“T7”,“T8”,“P3”,“P4”,]
info = mne.create_info(ch_names=ch_names, ch_types=[“eeg”]*16, sfreq=200)
raw = mne.io.RawArray(data, info, verbose=False)
raw.plot()
raw.compute_psd().plot()

When I add ch_types in mne.create_info, the μV of the plot image is very large, and when I delete it, the psd image cannot be displayed normally

If I delete, plot shows well but psd have problem

[mscheltienne (Mathieu Scheltienne)]

Hello,

MNE expects EEG data to be in Volts. Clearly, your data is not scaled correctly.
Regardless of the scale, you can set scalings="auto" to adapt the Y-range of the plot: raw.plot(scalings="auto") and you can use the +/- keys to interactively change the scale.

That said, I would strongly recommend to multiply data by the correct scaling to transform your data in Volts.

FYI, when you deleted the ch_types argument from create_info, it defaulted to 'misc', i.e. miscellaneous. As mentioned in the docstring of create_info, this is not a data channel type; thus when the PSD functions looks for data channels, it did not find any.

Mathieu

[spbgzh (guozihan)]

Thank you for your help, with your help I have processed the data correctly

data = list(map(lambda x: x / 1000000, list(map(lambda i: raw_data[file_name][i], index_list))))