Selecting all rows with the first 5 different values of a list

Question

I have a predefined list with 100 elements, whose values represent cluster labels. First, I would like to find the first 5 different cluster labels from the list. Then, I want to select all rows that have one of the five values as entry, and finally write their index and label into a new array.

How do I have to adjust my code to achive that? I think I have to use a loop, but since I am new to python I dont know how to set it correctly.

list = np.array(list)

new_array = []
for x in list:
  new_array.append(list[index, value]) 
print(new_array)

Answer 1

You can use np.unique to get the unique values of a list:

first_vals = np.unique(list)[:5]

new_array = []
for index, value in enumerate(list):
    if value in first_vals:
        new_array.append([index, value])
print(new_array)

Output:

[[0, 0], [1, 0], [2, 1], [3, 0], [4, 2], [5, 1], [6, 3], [10, 4], [11, 4], [12, 1], [14, 3], [15, 1], [16, 3], [17, 2], [18, 3]]

(Note: it's bad practice use names of Python builtins as variable names, e.g. list