Convert series of numbers to array in Python

Question

I want to convert series of numbers in to arrays in Python without using any libraries. ( 0,2 3,0 4,5 7,8 8,6 9,5 13,6 15,9 17,10 21,8) (1,3 3,4 5,9 7,5 10,2 11,4 20,10 ) (0,0 6,6 12,3 19,6 (green)) for example these three series. Is it possible to do it without libraries like numpy? I tried to use numpy but and reached the solution like this for the first series.

array([[ 0,  2],
       [ 3,  0],
       [ 4,  5],
       [ 7,  8],
       [ 8,  6],
       [ 9,  5],
       [13,  6],
       [15,  9],
       [17, 10],
       [21,  8]])

but the professor did not accept that.

How are this series provided to you?...what is the initial data structure?...string...generator...or what? — Iron Fist
– Iron Fist, Commented Apr 2, 2016 at 19:43
I Am given the following input in coordinates x,y: 0,2 3,0 4,5 7,8 8,6 9,5 13,6 15,9 17,10 21,8 1,3 3,4 5,9 7,5 10,2 11,4 20,10 0,0 6,6 12,3 19,6 — ss2
– ss2, Commented Apr 2, 2016 at 20:13

Ulf Aslak · Accepted Answer · 2016-04-02 20:54:26Z

1

If

a = "1,2 2,3 3,4 ..."

then

result = [map(int, v.split(",")) for v in a.split()]

Will give you

print result
[[1, 2], [2, 3], [3, 4], ... ]

answered Apr 2, 2016 at 20:54

Ulf Aslak

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Comments

Andrii Kozin · Accepted Answer · 2016-04-02 20:36:31Z

0

If series of numbers are string line then you could try next code:

a = "0,2 3,0 4,5 7,8 8,6 9,5 13,6 15,9 17,10 21,8"

lines = a.split(' ')
arr = [[int(i) for i in x.split(',')] for x in lines]
print arr

output

[[0, 2], [3, 0], [4, 5], [7, 8], [8, 6], [9, 5], [13, 6], [15, 9], [17, 10], [21, 8]]

EDIT (avoid O(n^2)):

One way passing:

a = "0,2 3,0 4,5 7,8 8,6 9,5 13,6 15,9 17,10 21,8"    
position = 0
previous_position = 0
final_array = []
temp_array = []
for character in a:
    if character == ',':
        temp_array = []
        temp_array.append(int(a[previous_position:position]))
        previous_position = position
    elif character == ' ':
        temp_array.append(int(a[previous_position+1:position]))
        previous_position = position+1
        final_array.append(temp_array)
    elif position == len(a) - 1:
        temp_array.append(int(a[previous_position+1:]))
        final_array.append(temp_array)

    position += 1

print final_array

edited Apr 2, 2016 at 20:36

answered Apr 2, 2016 at 19:24

Andrii Kozin

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1 Comment

ss2 Over a year ago

Thanks a lot. It works. But for the sake of complexity it runs O(n^2) because of the nested loop. Is there any way to it in O(n)??

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