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Shift the zero frequency to the centre

Source: R/helpers.R
fft_shift.Rd

fft_shift() rotates each chosen dimension of x by floor(n / 2), so that the zero-frequency entry of a transform sits in the middle; fft_ishift() undoes it. They are SciPy's fftshift() and ifftshift(). dim, dimnames and names move with the values.

Usage

fft_shift(x, axes = NULL)

fft_ishift(x, axes = NULL)

Arguments

x

A vector or array.

axes

The dimensions to shift, 1-based. NULL means all of them.

Value

x, rotated.

See also

Other helpers: fft_freq(), fft_next_len()

Examples

fft_shift(fft_freq(8))
#> [1] -0.500 -0.375 -0.250 -0.125  0.000  0.125  0.250  0.375
fft_ishift(fft_shift(1:7))
#> [1] 1 2 3 4 5 6 7