# [Tutor] create numpy array from list of strings

Danny Yoo dyoo at cs.wpi.edu
Wed Jun 4 00:04:22 CEST 2008

```> Hello, I have a list of strings:
> data =
> [ '33386.47    2.22    -1.11   0.43'
> '33386.67     3.33     -1.23  0.54'
> ...
> '46728.47    0.1    -1.87    -0.54'
> '46728.47    9.7    5.68    0.38'
> '46729.47    -0.17    -0.47    0.23']
>
> I wish to convert it to a numpy array of floats. How do I accomplish
> this?

Pointers:

* Give a name to the thing you're trying to define.  It sounds like
you're trying to define a function that takes a list of strings and
converts it to a numpy array.  Give it a good, concise name.  For
example, "convertStringsToNumpyArray" might be a bit wordy, but it
works.

* Write out your expectations on what this function will do on small
examples.  That way, once you have the function written, you can test
it.  For example:

convertStringsToNumpyArray['42']  ==>  the singleton array containing 42

convertStringToNumpyArray['3 1 4'] ==> the row array containing 3, 1,
and 4.

Cook up a few more examples for yourself.

* Try to simplify the problem slightly.  If you had a list of the number
rows, would you be able to turn that into a numpy array?  i.e. if you
were given:

data = [[1, 2],  ## row 1
[3, 4],  ## row 2
]

could you write a function that consumes that data and converts it into
a numpy array?
```