Report

Understanding the FFT Algorithm

Fixed Python 3.12 · checked 17 Oct 2026 · model cost $0.022

The tutorial's FFT implementation failed under Python 3 because the '/' operator produced floats used as slice indices, raising a TypeError. Replacing '/' with '//' for integer division resolved the error, allowing the code to run correctly.

2 changes to make it work today

Define recursive FFT

s5 · run_code migrate

Change N/2 to N//2 so slice indices are integers in Python 3.

@@ -12,4 +12,4 @@

X_odd = FFT(x[1::2])

factor = np.exp(-2j * np.pi * np.arange(N) / N)

- return np.concatenate([X_even + factor[:N / 2] * X_odd,

- X_even + factor[N / 2:] * X_odd])

+ return np.concatenate([X_even + factor[:N // 2] * X_odd,

+ X_even + factor[N // 2:] * X_odd])

Sources

TypeError: slice indices must be integers or None or have an __index__ method - LEfSe - The bioBakery help forumdverma2@EB-ONC-J8Q3FF3:/mnt/f/coin/LEfSe/pathway$ lefse\_plot\_res.py res\_pathway.res Pathway\_small.png Traceback (most recent call last): File “/home/dverma2/miniforge3/bin/lefse\_plot\_res.py”, line 10, in sys.exit(plot\_res()) File “/home/dverma2/miniforge3/lib/python3.10/site-packages/lefse/lefse\_plot\_res.py”, line 177, in plot\_res else: plot\_histo\_hor(params[‘output\_file’],params,data,len(data[‘cls’]) == 2,params[‘report\_features’]) File “/home/dverma2/miniforge3/lib/python3.10/site-packages/lefse/lefse\_plot\_res.py”, line 104, in plot\_histo\_hor if len(rr) > params[‘max\_featu
Slice indices must be integers or None or have an __index | Career KarmaThe “TypeError: slice indices must be integers or None or have an \_\_index\_\_ method” error is raised when you try to slice a list using a value that is not an integer, such as a float. [...] # Python TypeError: slice indices must be integers or None or have an \_\_index\_\_ method Solution
Lefse_plot_res.py plot error - TypeError: slice indices must be integers or None or have an __index__ method - LEfSe - The bioBakery help forumFile "/miniconda/envs/myenv/lib/python3.7/site-packages/lefse/lefse_plot_res.py", line 104, in plot_histo_hor if len(rr) > params['max_feature_len']: rr = rr[:params['max_feature_len']/2-2]+" [..]"+rr[-params['max_feature_len']/2+2:] TypeError: slice indices must be integers or None or have an __index__ method` [...] UNMAPPED 5.698806339377007 MF 4.992992452183536 0.0020039311821839286 UNINTEGRATED 5.534112533646385 NM 4.691403253999157 0.0016752988184979575 UNINTEGRATED.g\_\_Achromobacter\_s\_\_Achromobacter\_denitrificans 1.8462237235380918 - UNINTEGRATED.g\_\_Achromobacter\_s\_\_Achromobact

Define vectorized FFT

s8 · run_code migrate

Change X.shape[1]/2 to X.shape[1]//2 so slice indices are integers in Python 3.

@@ -19,6 +19,6 @@

# build-up each level of the recursive calculation all at once

while X.shape[0] < N:

- X_even = X[:, :X.shape[1] / 2]

- X_odd = X[:, X.shape[1] / 2:]

+ X_even = X[:, :X.shape[1] // 2]

+ X_odd = X[:, X.shape[1] // 2:]

factor = np.exp(-1j * np.pi * np.arange(X.shape[0])

/ X.shape[0])[:, None]

Sources

TypeError: slice indices must be integers or None or have an __index__ method - LEfSe - The bioBakery help forumdverma2@EB-ONC-J8Q3FF3:/mnt/f/coin/LEfSe/pathway$ lefse\_plot\_res.py res\_pathway.res Pathway\_small.png Traceback (most recent call last): File “/home/dverma2/miniforge3/bin/lefse\_plot\_res.py”, line 10, in sys.exit(plot\_res()) File “/home/dverma2/miniforge3/lib/python3.10/site-packages/lefse/lefse\_plot\_res.py”, line 177, in plot\_res else: plot\_histo\_hor(params[‘output\_file’],params,data,len(data[‘cls’]) == 2,params[‘report\_features’]) File “/home/dverma2/miniforge3/lib/python3.10/site-packages/lefse/lefse\_plot\_res.py”, line 104, in plot\_histo\_hor if len(rr) > params[‘max\_featu
Slice indices must be integers or None or have an __index | Career KarmaThe “TypeError: slice indices must be integers or None or have an \_\_index\_\_ method” error is raised when you try to slice a list using a value that is not an integer, such as a float. [...] # Python TypeError: slice indices must be integers or None or have an \_\_index\_\_ method Solution
Lefse_plot_res.py plot error - TypeError: slice indices must be integers or None or have an __index__ method - LEfSe - The bioBakery help forumFile "/miniconda/envs/myenv/lib/python3.7/site-packages/lefse/lefse_plot_res.py", line 104, in plot_histo_hor if len(rr) > params['max_feature_len']: rr = rr[:params['max_feature_len']/2-2]+" [..]"+rr[-params['max_feature_len']/2+2:] TypeError: slice indices must be integers or None or have an __index__ method` [...] UNMAPPED 5.698806339377007 MF 4.992992452183536 0.0020039311821839286 UNINTEGRATED 5.534112533646385 NM 4.691403253999157 0.0016752988184979575 UNINTEGRATED.g\_\_Achromobacter\_s\_\_Achromobacter\_denitrificans 1.8462237235380918 - UNINTEGRATED.g\_\_Achromobacter\_s\_\_Achromobact

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