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+--- Thread: Filter out all words that begin with P, B, or T. (/thread-18097.html)
Filter out all words that begin with P, B, or T. - johneven - May-05-2019
Need help with the following:
Filter out all words that begin with P, B, or T.
colors = ["Red", "Orange", "Yellow", "Green", "Blue", "Indigo", "Violet", "Purple", "Pink", "Brown", "Teal", "Turquois", "Peach", "Beige"]
#my response below-
for position in range(len(colors)):
color = colors[position]
print(color)
if color[0] in ["P", "B", "T"]:
del colors[position]
print(colors)Output:Red
Orange
Yellow
Green
Blue #?
Violet
Purple #?
Brown #?
Turquois #?
Beige #?RE: Filter out all words that begin with P, B, or T. - Yoriz - May-05-2019
The position indexes are based on a full list, as soon as something is deleted from the list those indexes no longer relate to the correct position and there will be a
IndexError: list index out of range because the list will no longer be big enough.Rather then trying to alter the original list you should make a new list and only add the non filtered items to it.
After this is complete the original list variable can be assigned to the new list
RE: Filter out all words that begin with P, B, or T. - perfringo - May-06-2019
You can combine string method .startswith and list comprehension with conditional to get desired result. This one of the most straightforward translations of spoken language into Python: "give me color for every color in colors which is not starting with letters 'P', 'B', 'T'":
>>> [color for color in colors if not color.startswith(('P', 'B', 'T'))]
['Red', 'Orange', 'Yellow', 'Green', 'Indigo', 'Violet']
RE: Filter out all words that begin with P, B, or T. - michalmonday - May-07-2019
Alternatively:
import re
colors = ["Red", "Orange", "Yellow", "Green", "Blue", "Indigo", "Violet", "Purple", "Pink", "Brown", "Teal", "Turquois", "Peach", "Beige"]
filtered_colors = list(filter(re.compile('[^PBT]').match, colors))
print(filtered_colors)Output:['Red', 'Orange', 'Yellow', 'Green', 'Indigo', 'Violet']