in_place_vs_new_list.py

import pandas as pd
import matplotlib.pyplot as plt
import time

def filter_items_newlist(items, item):
    return [x for x in items if x != item]

def filter_items_inplace_gen(items, item):
    items[:] = (x for x in items if x != item)

def filter_items_inplace(items, item):
    ix_dst = 0
    for ix_src, x in enumerate(items):
        if x != item:
            items[ix_dst] = x
            ix_dst += 1
    del items[ix_dst:]

def time_func(N, f):
    items = list(range(N))
    start = time.perf_counter()
    f(items, N)
    stop = time.perf_counter()
    return stop - start

NS = range(0, 1_000_000, 10_000)
inplc = [time_func(n, filter_items_inplace) for n in NS]
inplc_gen = [time_func(n, filter_items_inplace_gen) for n in NS]
new = [time_func(n, filter_items_newlist) for n in NS]

df = pd.DataFrame({"in-place":inplc, "in-place-gen": inplc_gen, "new-list":new}, index=NS)

df.plot()
plt.savefig('in-place-vs-new-list-filter.png')

Note, this is really the best-case difference for the in-place algorithm, since nothing is actually removed, since N is never in the list!