How to insert a string into a numpy list every nth index?

Question

Let's say i have a list like this one:

b = np.array(['a','b','c','a','b','c','a','b','c','a','b','c'])

and i wanted to insert this character at every 17th position '\n':

np.insert(b,b[::16],'\n')

why do i get this error message and how would be a corect way to do this?

ValueError: invalid literal for int() with base 10: 'a'

Thank you very much

akuiper · Accepted Answer · 2017-01-16 15:55:49Z

4

The second argument for np.insert should be the index to place the values, you can try:

n = 3
np.insert(b, range(n, len(b), n), "\n") 

# array(['a', 'b', 'c', '\n', 'a', 'b', 'c', '\n', 'a', 'b', 'c', '\n', 'a',
#        'b', 'c'], 
#       dtype='<U1')

edited Jan 16, 2017 at 15:55

answered Jan 16, 2017 at 15:49

akuiper

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1 Comment

user3759978 Over a year ago

Nice, thank you! I kinda misread numpy.insert needing a slice of indices ;)

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