How to find numbers larger than X in a list

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1

As an example, this code there

N=[1,2,3,4,5]
B= #quantidade de números maiores que 2
print(B)

'B' would be the number of numbers greater than 2 present in the list, for example.

python

4 answers

4

The logic is exactly the same to filter elements from a list:

Filter elements from a Python list

The simplest and most direct is to use list comprehension:

B = len([i for i in N if i > 2])

In this case, we use the function len to calculate the amount of elements.

See working on Ideone.

Another way, equivalent to list comprehension, is to use the function filter:

B = filter(lambda i: i > 2, N)

However, the return of this function will be a generator, thus requiring the conversion to list to get its length:

B = len(list(filter(lambda i: i > 2, N)))

But for this solution, this method becomes unviable compared to the first.

See working on Ideone.

3


To simplify you can use like this:

minha_lista = [1,2,3,4,5]
maior_que = 2

filtrados = [x for x in minha_lista if x > maior_que]

#exibe os elementos
print(filtrados)

#conta os elementos
print(len(filtrados))
  • 1

    A lot more simplified than my answer, I’m still learning, and a lot.

  • @Wéllingthonm.Souza is one of the things I like about Python, I was reluctant to migrate to Python3.6 (I was "caught" in 2.7), but everything so far has pleased me, I’m happy to know that you are interested in language too :D

0

Here a solution, there can be easier and smaller

lista = [1,2,3,4,5,6,7,8,9,1,23]
X = 0
B = 0 # Armazena a quantidade de números maiores que 2
num_elementos_lista = len(lista)
while(X < num_elementos_lista):
    if lista[X] > 2: # verifica se lista[X] é maior que 2
      B+=1 # Se for incrementa + 1 em B
    X+=1

print(B)

See working on repl

  • I believe I have understood your idea and it is not all bad, but the implementation is wrong. Replace the list by [1, 1, 1, 1, 1] and see what happens. The expected result is 0, but... See if you understand the reason.

  • @Andersoncarloswoss actually I missed something at the time, I was checking to see if X was greater than 2, being that it was to verify lista[X] > 2

  • Perfect, now a suggestion that would make your solution more pythonica: to browse values from a list avoid using the while with the len, because it is a vice of other languages that is not only seen badly in the community as the performance is less. For this, prefer to use for n in lista, where in that case the n will be the values of the list, can do if n > 2: ..., no longer needing the len or the control variable X. See: https://ideone.com/8bghU2, which is nothing more than expanded list comprehension.

  • @Interesting andersoncarloswoss, vlw by tip.

0

If you intend apenas know the quantidade of values greater than a given value, which in this case is 2, you can implement a repeat loop and check the sum of all numbers larger than 2.

For this you can implement the following code...

N = [1, 2, 3, 4, 5]
cont = 0
for c in N:
    if c > 2:
        cont += 1

print(f'\033[32mA quantidade dos números maiores que "2" é: {cont}')

Note the functioning of the algorithm in repl it..

Note that in this algorithm I implemented a loop of repetition for, where he traverses the aforementioned list ([1, 2, 3, 4, 5]).

Then I defined a if where you will check each elemento from the list. If the widget is maior that 2 the counting variable shall be incrementada. And then displays the amount of values greater than 2.

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