In C#, with LINQ, if I have en enumeration enumerable
, I can do:
// a: Does the enumerable contain an item that satisfies the lambda?
bool contains = enumerable.Any(lambda);
// b: How many items satisfy the lambda?
int count = enumerable.Count(lambda);
// c: Return an enumerable that contains only distinct elements according to my custom comparer
var distinct = enumerable.Distinct(comparer);
// d: Return the first element that satisfies the lambda, or throws an exception if none
var element = enumerable.First(lambda);
// e: Returns an enumerable containing all the elements except those
// that are also in 'other', equality being defined by my comparer
var except = enumerable.Except(other, comparer);
I hear that Python has a more concise syntax than C# (and is therefore more productive), so how do I achieve the same with an iterable in Python, with the same amount of code, or less?
Note: I don't want to materialize the iterable into a list if I don't have to (Any
, Count
, First
).
The following Python lines should be equivalent to what you have (assuming func
, or lambda
in your code, returns a Boolean):
# Any
contains = any(func(x) for x in enumerable)
# Count
count = sum(func(x) for x in enumerable)
# Distinct: since we are using a custom comparer here, we need a loop to keep
# track of what has been seen already
distinct = []
seen = set()
for x in enumerable:
comp = comparer(x)
if not comp in seen:
seen.add(comp)
distinct.append(x)
# First
element = next(iter(enumerable))
# Except
except_ = [x for x in enumerable if not comparer(x) in other]
References:
Note that I renamed lambda
to func
since lambda
is a keyword in Python, and I renamed except
to except_
for the same reason.
Note that you could also use map()
instead of the comprehensions/generators, but it is generally considered less readable.