Frequency array generation (fftfreq) in SciPy - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the fftfreq function from scipy.fft module.

SciPy

from scipy.fft import [1]

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Afft

Bfftshift

Cifft

Dfftfreq

Attempts:

3 left

💡 Hint

Common Mistakes

Importing 'fft' instead of 'fftfreq'.

Using 'ifft' which is inverse FFT.

Importing 'fftshift' which shifts zero frequency.

The fftfreq function is imported from scipy.fft to generate frequency bins for FFT.

2fill in blank

medium

Complete the code to generate frequency bins for a signal of length 8.

SciPy

freqs = fftfreq([1])

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A8

B16

C4

D10

Attempts:

3 left

💡 Hint

Common Mistakes

Using a number larger or smaller than the signal length.

Confusing frequency bins count with sampling rate.

The length of the signal is 8, so fftfreq(8) generates 8 frequency bins.

3fill in blank

hard

Fix the error in the code to generate frequency bins with a sample spacing of 0.5 seconds.

SciPy

freqs = fftfreq(10, [1]=0.5)

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Ad

Bdt

Cspacing

Dsample_spacing

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'dt' or 'spacing' which are not valid parameter names.

Passing sample spacing as a positional argument instead of keyword.

The correct parameter name for sample spacing in fftfreq is d.

4fill in blank

hard

Fill both blanks to create a frequency array for 12 samples with sample spacing 0.1 seconds.

SciPy

freqs = fftfreq([1], [2]=0.1)

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A12

B10

Cd

Ddt

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong parameter name for sample spacing.

Using incorrect number of samples.

The first argument is the number of samples (12), and the sample spacing parameter is d.

5fill in blank

hard

Fill all three blanks to create a dictionary mapping frequencies to their indices for 6 samples with spacing 0.2 seconds, including only positive frequencies.

SciPy

freqs = fftfreq([1], [2]=0.2)
positive_freqs = {i: f for i, f in enumerate(freqs) if f [3] 0}

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A6

Bd

C>

D<

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong comparison operator to filter frequencies.

Using incorrect parameter name for sample spacing.

Using wrong number of samples.

We use 6 samples, sample spacing parameter d, and filter frequencies greater than zero.