Questions tagged [filter]
A program or routine that rejects or accepts data that meets a given criterion. An example would be a filter that removed entries less than a given limit from a set of values. Do NOT use this tag for: Signal or image processing, use [filtering]. Java servlet filters. Use [servlet-filters]. For Bloom filters, use [bloom-filter]. For CSS filters use [css-filters].
filter
32,398
questions
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List comprehension vs. lambda + filter
I have a list that I want to filter by an attribute of the items.
Which of the following is preferred (readability, performance, other reasons)?
xs = [x for x in xs if x.attribute == value]
xs = ...
- 19.1k
1083
votes
20
answers
2.4m
views
Remove rows with all or some NAs (missing values) in data.frame
I'd like to remove the lines in this data frame that:
a) contain NAs across all columns. Below is my example data frame.
gene hsap mmul mmus rnor cfam
1 ENSG00000208234 0 NA NA ...
- 12k
774
votes
31
answers
883k
views
How to filter a Java Collection (based on predicate)?
I want to filter a java.util.Collection based on a predicate.
- 14.8k
635
votes
10
answers
533k
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How to filter empty or NULL names in a QuerySet?
I have first_name, last_name & alias (optional) which I need to search for. So, I need a query to give me all the names that have an alias set.
Only if I could do:
Name.objects.filter(alias!="")
...
- 18.2k
516
votes
31
answers
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Filter object properties by key in ES6
Let's say I have an object:
{
item1: { key: 'sdfd', value:'sdfd' },
item2: { key: 'sdfd', value:'sdfd' },
item3: { key: 'sdfd', value:'sdfd' }
}
I want to create another object by filtering ...
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votes
2
answers
110k
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Why is `[` better than `subset`?
When I need to filter a data.frame, i.e., extract rows that meet certain conditions, I prefer to use the subset function:
subset(airquality, Month == 8 & Temp > 90)
Rather than the [ function:
...
- 88.7k
372
votes
8
answers
346k
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How to use filter, map, and reduce in Python 3
This is how I am accustomed to filter, map, and reduce working in Python 2:
>>> def f(x):
return x % 2 != 0 and x % 3 != 0
>>> filter(f, range(2, 25))
[5, 7, 11, 13, 17, 19, ...
- 12.6k
371
votes
8
answers
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File input 'accept' attribute - is it useful?
Implementing a file upload under html is fairly simple, but I just noticed that there is an 'accept' attribute that can be added to the <input type="file" ...> tag.
Is this attribute useful as ...
- 9,186
345
votes
24
answers
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How to filter an array from all elements of another array
I'd like to understand the best way to filter an array from all elements of another one. I tried with the filter function, but it doesn't come to me how to give it the values i want to remove. ...
- 6,135
337
votes
4
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Java 8 Streams: multiple filters vs. complex condition
Sometimes you want to filter a Stream with more than one condition:
myList.stream().filter(x -> x.size() > 10).filter(x -> x.isCool()) ...
or you could do the same with a complex condition ...
- 91.3k
335
votes
11
answers
370k
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remove None value from a list without removing the 0 value
This was my source I started with.
My List
L = [0, 23, 234, 89, None, 0, 35, 9]
When I run this :
L = filter(None, L)
I get this results
[23, 234, 89, 35, 9]
But this is not what I need, what ...
- 5,714
319
votes
5
answers
719k
views
Filter rows which contain a certain string
I have to filter a data frame using as criterion those row in which is contained the string RTB.
I'm using dplyr.
d.del <- df %>%
group_by(TrackingPixel) %>%
summarise(MonthDelivery = as....
- 6,567
315
votes
1
answer
164k
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How to query Case-insensitive data in Django ORM?
How can I query/filter in Django and ignore the cases of my query-string?
I've got something like and like to ignore the case of my_parameter:
MyClass.objects.filter(name=my_parameter)
- 23.1k
307
votes
7
answers
346k
views
How to filter a dictionary according to an arbitrary condition function?
I have a dictionary of points, say:
>>> points={'a':(3,4), 'b':(1,2), 'c':(5,5), 'd':(3,3)}
I want to create a new dictionary with all the points whose x and y value is smaller than 5, i.e. ...
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298
votes
3
answers
156k
views
How to make Regular expression into non-greedy?
I'm using jQuery. I have a string with a block of special characters (begin and end). I want get the text from that special characters block. I used a regular expression object for in-string finding. ...
- 3,507