How can I put a string to an array

Question

I want to put a string to an array location but I get an error:

ValueError: could not convert string to float

My code is the following:

k = np.ceil(99/8)

rs = np.zeros((int(k), 10))

for i in range(0, int(k)):
    rs[i, 0] = "FREQ"
    for j in range(1,9):
        rs[i, j] = rs_imp[8*k+j, 0]

Maybe this post is what you are actually looking to perform. — Nickil Maveli
– Nickil Maveli, Commented Jun 8, 2016 at 19:24

Riaz · Accepted Answer · 2016-06-08 23:07:40Z

2

Your array is implicitly a float array, but you can change the data type to object to be able to include both floats and strings:

rs = np.zeros((int(k), 10), dtype='object')

But this is going to rob you of potential optimizations and may cause unexpected problems later on.

Sounds like an XY problem. Why do you think you need to add the string "FREQ" into this array? What are you really trying to do?

edited Jun 8, 2016 at 23:07

answered Jun 8, 2016 at 19:28

Riaz

8746 silver badges15 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

Kostas Belivanis Over a year ago

It is a XY problem that I want to separate and create files with specific format so that I can use the XY as an input. Thank you very very much. It worked this way.

Kostas Belivanis Over a year ago

How can I write that array now to a .txt file though? When I tried to do np.savetxt('test.txt', rsf, delimiter=',') I got Mismatch between array dtype ('object') and format specifier ('%.18e,%.18e,%.18e,%.18e,%.18e,%.18e,%.18e,%.18e,%.18e')

Riaz Over a year ago

Because the array is no longer of type float, the default formatting codes (like %e) are not valid. You could do this: np.savetxt('test.txt', rsf, delimiter=',', fmt='%s') and it should do what you need, but if the point of the question was to add "FREQ" as a prefix to each line of a file containing numbers, there are cleaner ways to achieve this than to create a mixed-type array. By the way, an XY problem is defined here.

quantummind · Accepted Answer · 2016-06-08 19:09:12Z

2

You have an array of floats. You want to put a string value to an element of that array. It is not possible.

answered Jun 8, 2016 at 19:09

quantummind

2,1461 gold badge15 silver badges20 bronze badges

Collectives™ on Stack Overflow

How can I put a string to an array

2 Answers 2

3 Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

3 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related