Removing elements from a list containing specific characters
Question:
I want to remove all elements in a list which contains (or does not contain) a set of specific characters, however I’m running in to problems iterating over the list and removing elements as I go along. Two pretty much equal examples of this is given below. As you can see, if two elements which should be removed are directly following each other, the second one does not get removed.
Im sure there are a very easy way to do this in python, so if anyone know it, please help me out – I am currently making a copy of the entire list and iterating over one, and removing elements in the other…Not a good solution I assume
>>> l
['1', '32', '523', '336']
>>> for t in l:
... for c in t:
... if c == '2':
... l.remove(t)
... break
...
>>> l
['1', '523', '336']
>>> l = ['1','32','523','336','13525']
>>> for w in l:
... if '2' in w: l.remove(w)
...
>>> l
['1', '523', '336']
Figured it out:
>>> l = ['1','32','523','336','13525']
>>> [x for x in l if not '2' in x]
['1', '336']
Would still like to know if there is any way to set the iteration back one set when using for x in l though.
Answers:
List comprehensions:
l = ['1', '32', '523', '336']
[ x for x in l if "2" not in x ]
# Returns: ['1', '336']
[ x for x in l if "2" in x ]
# Returns: ['32', '523']
l = ['1', '32', '523', '336']
stringVal = "2"
print(f"{[ x for x in l if stringVal not in x ]}")
# Returns: ['1', '336']
print(f"{[ x for x in l if stringVal in x ]}")
# Returns: ['32', '523']
If I understand you correctly,
Example:
l = ['1', '32', '523', '336']
[x for x in l if "2" not in x]
# Returns: ['1', '336']
fString Example:
l = ['1', '32', '523', '336']
stringVal = "2"
print(f"{[x for x in l if stringVal not in x]}")
# Returns: ['1', '336']
might do the job.
Problem you could have is that you are trying to modify the sequence l same time as you loop over it in for t loop.
In addition to @Matth, if you want to combine multiple statements you can write:
l = ['1', '32', '523', '336']
[ x for x in l if "2" not in x and "3" not in x]
# Returns: ['1']
fString Example
l = ['1', '32', '523', '336']
stringValA = "2"
stringValB = "3"
print(f"{[ x for x in l if stringValA not in x and stringValB not in x ]}")
# Returns: ['1']
I want to remove all elements in a list which contains (or does not contain) a set of specific characters, however I’m running in to problems iterating over the list and removing elements as I go along. Two pretty much equal examples of this is given below. As you can see, if two elements which should be removed are directly following each other, the second one does not get removed.
Im sure there are a very easy way to do this in python, so if anyone know it, please help me out – I am currently making a copy of the entire list and iterating over one, and removing elements in the other…Not a good solution I assume
>>> l
['1', '32', '523', '336']
>>> for t in l:
... for c in t:
... if c == '2':
... l.remove(t)
... break
...
>>> l
['1', '523', '336']
>>> l = ['1','32','523','336','13525']
>>> for w in l:
... if '2' in w: l.remove(w)
...
>>> l
['1', '523', '336']
Figured it out:
>>> l = ['1','32','523','336','13525']
>>> [x for x in l if not '2' in x]
['1', '336']
Would still like to know if there is any way to set the iteration back one set when using for x in l though.
List comprehensions:
l = ['1', '32', '523', '336']
[ x for x in l if "2" not in x ]
# Returns: ['1', '336']
[ x for x in l if "2" in x ]
# Returns: ['32', '523']
l = ['1', '32', '523', '336']
stringVal = "2"
print(f"{[ x for x in l if stringVal not in x ]}")
# Returns: ['1', '336']
print(f"{[ x for x in l if stringVal in x ]}")
# Returns: ['32', '523']
If I understand you correctly,
Example:
l = ['1', '32', '523', '336']
[x for x in l if "2" not in x]
# Returns: ['1', '336']
fString Example:
l = ['1', '32', '523', '336']
stringVal = "2"
print(f"{[x for x in l if stringVal not in x]}")
# Returns: ['1', '336']
might do the job.
Problem you could have is that you are trying to modify the sequence l same time as you loop over it in for t loop.
In addition to @Matth, if you want to combine multiple statements you can write:
l = ['1', '32', '523', '336']
[ x for x in l if "2" not in x and "3" not in x]
# Returns: ['1']
fString Example
l = ['1', '32', '523', '336']
stringValA = "2"
stringValB = "3"
print(f"{[ x for x in l if stringValA not in x and stringValB not in x ]}")
# Returns: ['1']