convert a list to an array, out put has no comma-CodePudding

I tried to convert a list to an array, but the output I got has no comma.

%%writefile tem2504.txt
1 2 3 4 5 6
2 3 5 8 7 9

data = []
with open('tem2504.txt') as f:
    for line in f:
        numbers = line.split()
        print(numbers)
        print('hello')
        for number in numbers:
            data.append(float(number))
print(data)
print(type(data))
print(np.array(data))
print(type(np.array(data)))

But the out put I got has no comma between the numbers: [1. 2. 3. 4. 5. 6. 2. 3. 5. 8. 7. 9.]

['1', '2', '3', '4', '5', '6']
hello
['2', '3', '5', '8', '7', '9']
hello
[1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 2.0, 3.0, 5.0, 8.0, 7.0, 9.0]
<class 'list'>
[1. 2. 3. 4. 5. 6. 2. 3. 5. 8. 7. 9.]
<class 'numpy.ndarray'>

Why is that? Thank you!

CodePudding user response：

This is simply how numpy displays arrays. Even in case of lists, there is no actual use of commas they are just for display.

CodePudding user response：

That's just the way numpy outputs its array type as a string. It doesn't use comas, but it still functions as a list of floats. If you use the following:

import numpy as np
a = [1.0, 2.0, 3.0, 4.0, 5.0, 6.0, 2.0, 3.0, 5.0, 8.0, 7.0, 9.0]
np_array = np.array(a)
for i in np_array:
     print(i)

It will list iterate through the np.array as a list:

1.0
2.0
3.0
4.0
5.0
6.0
2.0
3.0
5.0
8.0
7.0
9.0

CodePudding user response：

You don't need to worry due to the absence of commas in the array. That's just something numpy does to display them. It doesn't affect how the arrays work.

CodePudding user response：

In [214]: alist = [0,1,2,3]

This display/print of a list has [] and ,

In [215]: print(alist)
[0, 1, 2, 3]

The str display of an array omits the comma, as a clue that it is not a list:

In [216]: print(np.array(alist))
[0 1 2 3]

But every class also has repr format, that often is 'more informative':

In [217]: print(repr(np.array(alist)))
array([0, 1, 2, 3])