[Numpy-discussion] Finding the same value in List

Happyman bahtiyor_zohidov@mail...
Wed Apr 17 09:19:25 CDT 2013


 okay Todd, I got it.
There are some reasons why I preferred asking that question. Let me explain:

I am using Excel data which contains 3 columns and say 12 rows to process some simple data.
What I want to do with the code you provided is that In the first column A has data that indicates the same ID where 2nd and 3rd has the same value. In other words I will put the following sample data to explain better:

A_column = [ 22, 92, 64, 64, 77, 77, 64, 64, 22, 92, 99, 200 ]  # The same length 12
B_column = [ 8, 8, 8, 8, 8, 0, 0, 0, 0, 0, 12, 0]    # The same length 12
C_column = [ 0, 0, 0, 0, 0, 8, 8, 8, 8, 8, 4, 13]     # The same length 12 

The main reason for the question is as we discussed we already processed data in A_column. B_column has five "8" numbers
in C_column as well but not in the same index!!! I want to get the following result which really confused me in terms of 'dtype':
IF A_column the same THEN The value of B_column and C_columns in the ID (index, we got) is the same THEN
get B and C value otherwise NO...

I hope you would understand my problem


Среда, 17 апреля 2013, 12:34 +02:00 от Todd < toddrjen@gmail.com >:
>>The data type:
>>x in ndarray and x[ i ]--> int64
>>type(f)                     -->   ' list '
>>type( f[ 0 ] )             -->   ' tuple '
>>type( f[ 0][0] )          -->  'ndarray'
>>type( f[ 0 ][ 0 ][ 0]  ) -->  'int64'
>>
>>How do you think to avoid diversity if data type in this 
example? I think  it is not necessary to get diverse dtype as well as 
more than 1D array..
>That is why I suggested this approach was better ( note the that this is where()[0] instead of just where() as it was in my first example):
>
>x,i=numpy.unique(y, return_inverse=True)
>f=[numpy.where(i==ind)[0] for ind in range(len(x))]
>
>type(f)     --> list
>type(f[0]) --> ndarray
>
>type(f[0][0]) is meaningless since it is just a single element in an array.  It must be an int type of some sort of since indices have to be int types.  x will be the same dtype as your input array.
>
>You could conceivably change the type of f[0] to a list, but why would you want to?  One of the big advantages of python is that usually it doesn't matter what the type is.  In this case, a numpy ndarray will work the same as a list in most cases where you would want to use these sorts of indices. It is possibly to change the ndarray to a list, but unless there is a specific reason you need to use lists so then it is better not to.  
>
>You cannot change the list to an ndarray because the elements of the list are different lengths.  ndarray doesn't support that.
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