help: pandas and 2d table

[Mats Wichmann]

On 4/13/24 07:00, jak via Python-list wrote:
> Stefan Ram ha scritto:
>> jak <nospam at please.ty> wrote or quoted:
>>> Would you show me the path, please?
>>
>>    I was not able to read xls here, so I used csv instead; Warning:
>>    the script will overwrite file "file_20240412201813_tmp_DML.csv"!
>>
>> import pandas as pd
>>
>> with open( 'file_20240412201813_tmp_DML.csv', 'w' )as out:
>>      print( '''obj,foo1,foo2,foo3,foo4,foo5,foo6
>> foo1,aa,ab,zz,ad,ae,af
>> foo2,ba,bb,bc,bd,zz,bf
>> foo3,ca,zz,cc,cd,ce,zz
>> foo4,da,db,dc,dd,de,df
>> foo5,ea,eb,ec,zz,ee,ef
>> foo6,fa,fb,fc,fd,fe,ff''', file=out )
>>
>> df = pd.read_csv( 'file_20240412201813_tmp_DML.csv' )
>>
>> result = {}
>>
>> for rownum, row in df.iterrows():
>>      iterator = row.items()
>>      _, rowname = next( iterator )
>>      for colname, value in iterator:
>>          if value not in result: result[ value ]= []
>>          result[ value ].append( ( rowname, colname ))
>>
>> print( result )
>>
> 
> In reality what I wanted to achieve was this:
> 
>      what = 'zz'
>      result = {what: []}
> 
>      for rownum, row in df.iterrows():
>          iterator = row.items()
>          _, rowname = next(iterator)
>          for colname, value in iterator:
>              if value == what:
>                  result[what] += [(rowname, colname)]
>      print(result)
> 
> In any case, thank you again for pointing me in the right direction. I
> had lost myself looking for a pandas method that would do this in a
> single shot or almost.
> 
> 

doesn't Pandas have a "where" method that can do this kind of thing? Or 
doesn't it match what you are looking for?  Pretty sure numpy does, but 
that's a lot to bring in if you don't need the rest of numpy.