[Tutor] reading a string into an array

[bob gailer]

Kent Johnson wrote:
> On Sat, May 31, 2008 at 3:43 PM, Bryan Fodness <bryan.fodness at gmail.com> wrote:
>   
>> I am trying to read a long string of values separated by a backslash into an
>> array of known size.
>>
>> Here is my attempt,
>>
>> from numpy import *
>> ay, ax = 384, 512
>> a = zeros([ay, ax])
>> for line in open('out.out'):
>>     data = line.split('\\')
>>     
>
> Are you trying to accumulate all the lines into data? If so you should use
> data = []
> for line in open('out.out'):
>   data.extend(line.split('\\'))
>
>   
>> k = 0
>> for i in range(ay):
>>     for j in range(ax):
>>         a[i, j] = data[k]
>>         k+=1
>> but, I receive the following error.
>>
>> Traceback (most recent call last):
>>   File "C:/Users/bryan/Desktop/dose_array.py", line 13, in <module>
>>     a[i, j] = data[k]
>> ValueError: setting an array element with a sequence.
>>     
>
> I think this is because data is a list of strings, not numbers. Change
> my line above to
> data.extend(int(i) for i in line.split('\\'))
>
> But you don't have to create your array by copying every item. It is
> numpy, after all! I think this will work:
> data = []
> for line in open('out.out'):
>   data.extend(int(i) for i in line.split('\\'))
>   
Even more concise and possibly faster:

data = open('out.out').read().replace('\n', '\\').split('\\')
> a = array(data)
> a.shape = (384, 512)
>
> Kent
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>
>   


-- 
Bob Gailer
919-636-4239 Chapel Hill, NC