Python, remove all occurrences of string in list
Question:
Say i have a list:
main_list = ['bacon', 'cheese', 'milk', 'cake', 'tomato']
and another list:
second_list = ['cheese', 'tomato']
How can I remove all elements that are found in the second list, from the main list?
Answers:
If the order is not important you can use sets:
>>> main_array = ['bacon', 'cheese', 'milk', 'cake', 'tomato']
>>> second_array = ['cheese', 'tomato']
>>> set(main_array) & set(second_array)
set(['tomato', 'cheese'])
Here we use the intersection operator, &. Should you only want items not found in your second list, we can use difference, -:
>>> set(main_array) - set(second_array)
set(['cake', 'bacon', 'milk'])
new_array = [x for x in main_array if x not in second_array]
However, this is not very performant for large lists. You can optimize by using a set for second_array:
second_array = set(second_array)
new_array = [x for x in main_array if x not in second_array]
If the order of the items does not matter, you can use a set for both arrays:
new_array = list(set(main_array) - set(second_array))
main_array = set(['bacon', 'cheese', 'milk', 'cake', 'tomato'])
second_array = (['cheese', 'tomato'])
main_array.difference(second_array)
>>> set(['bacon', 'cake', 'milk'])
main_array.intersection(second_array)
>>> set(['cheese', 'tomato'])
l = [u'SQOOP', u'SOLR', u'SLIDER', u'SFTP', u'PIG', u'NODEMANAGER', u'JSQSH', u'HCAT', u'HBASE_REGIONSERVER', u'GANGLIA_MONITOR', u'FLUME_HANDLER', u'DATANODE', u'BIGSQL_WORKER']
p = [u'SQOOP', u'SOLR', u'SLIDER', u'SFTP']
l = [i for i in l if i not in [j for j in p]]
print l
[u'PIG', u'NODEMANAGER', u'JSQSH', u'HCAT', u'HBASE_REGIONSERVER', u'GANGLIA_MONITOR', u'FLUME_HANDLER', u'DATANODE', u'BIGSQL_WORKER']
Say i have a list:
main_list = ['bacon', 'cheese', 'milk', 'cake', 'tomato']
and another list:
second_list = ['cheese', 'tomato']
How can I remove all elements that are found in the second list, from the main list?
If the order is not important you can use sets:
>>> main_array = ['bacon', 'cheese', 'milk', 'cake', 'tomato']
>>> second_array = ['cheese', 'tomato']
>>> set(main_array) & set(second_array)
set(['tomato', 'cheese'])
Here we use the intersection operator, &. Should you only want items not found in your second list, we can use difference, -:
>>> set(main_array) - set(second_array)
set(['cake', 'bacon', 'milk'])
new_array = [x for x in main_array if x not in second_array]
However, this is not very performant for large lists. You can optimize by using a set for second_array:
second_array = set(second_array)
new_array = [x for x in main_array if x not in second_array]
If the order of the items does not matter, you can use a set for both arrays:
new_array = list(set(main_array) - set(second_array))
main_array = set(['bacon', 'cheese', 'milk', 'cake', 'tomato'])
second_array = (['cheese', 'tomato'])
main_array.difference(second_array)
>>> set(['bacon', 'cake', 'milk'])
main_array.intersection(second_array)
>>> set(['cheese', 'tomato'])
l = [u'SQOOP', u'SOLR', u'SLIDER', u'SFTP', u'PIG', u'NODEMANAGER', u'JSQSH', u'HCAT', u'HBASE_REGIONSERVER', u'GANGLIA_MONITOR', u'FLUME_HANDLER', u'DATANODE', u'BIGSQL_WORKER']
p = [u'SQOOP', u'SOLR', u'SLIDER', u'SFTP']
l = [i for i in l if i not in [j for j in p]]
print l
[u'PIG', u'NODEMANAGER', u'JSQSH', u'HCAT', u'HBASE_REGIONSERVER', u'GANGLIA_MONITOR', u'FLUME_HANDLER', u'DATANODE', u'BIGSQL_WORKER']