I want to sort an list so it contains all values that are not False

Question

I have this data:

  l = ['10 20 10 36 30 33 400 400 -1 -1', 
       '100 50 50 30 60 27 70 24 -2 -2 700 700', 
       '300 1000 80 21 90 18 100 15 110 12 120 9 900 900 -3 -3',
       '30 90 130 6 140 3 -4 -4 1000 1000']

  l = [e.split() for e in l]

  weight = [int(weight[0]) for weight in l]

So i and did the following code:

 for data in range(len(weight)):
    if weight[data] < 20 or weight[data] > 200:
        weight[data] = False
        print("Error: Index {:} in weight is out of range".format(data))

After my for loop, the weight variable looks like this:

  bool [False]
  int  [100]
  bool [False]
  int  [30]

I now want to redefine my weight variable, so it contains the values in weight which are not False:

  int  [100]
  int  [30]

Answer 1

Use list comprehension:

weight = [x for x in weight if x]

Better is this because False can be 0 too:

weight = [x for x in weight if x is not False]

Everything can be done with one list comprehension:

weight = [data for data in weight if data < 20 or data > 200]

Answer 2

Use numpy arrays:

arr=np.array(weight)  
weight=arr[arr >0]