How To: Delete columns of data

[Peter M. Brigham]

Yes. You split pData, which will alter the original table, and you don't restore it. Don't reference the parameter.

Still great, however!!

-- Peter

Peter M. Brigham
pmbrig at gmail.com
http://home.comcast.net/~pmbrig
On Sep 5, 2014, at 2:37 PM, Michael Doub wrote:

> just to complete your library, here is a function that will extract the listed column in the order that you 
> specify but it does not modify the original data.
> 
> -= Mike
> 
> 
> 
> function extractColumns @pData,pColsToReturn,pDelim
>   -- Extract specified columns from a table in order
>   -- Syntax: extractColumns <data>,<cols>[,<delim>]
>   --     data: Specifies the data to parse.
>   --     cols: A comma separated list of columns or column ranges to be returned in order
>   --         for example "2,7,5"
>   --         or a accending column range: "3-5"
>   --         of a decending column range: "5-3"
>   --         or a combination "2,4-5,7,11-9"
>   --     delim: Optional column separator for example "," or "|"
>   --         if unspecified, defaults to tab.
>   -- based on a handler by Hugh Senior and Peter M. Brigham, Use-LC list
> 
>   -- requires getItem()
> 
>   if pColsToReturn = empty then return pData
>   repeat for each item pCol in pColsToReturn
>      if "-" is in pCol then 
>         put getItem(pCol,1,"-") into firstColNbr
>         put getItem(pCol,2,"-") into lastColNbr
>         if firstColNbr < lastColNbr then
>            repeat with i = firstColNbr to lastColNbr
>               put i & comma after pColsToReturnExpanded
>            end repeat
>         else
>            repeat with i = firstColNbr down to lastColNbr
>               put i & comma after pColsToReturnExpanded
>            end repeat
>         end if
>      else
>         put pCol & comma after pColsToReturnExpanded
>      end if
>   end repeat
>   put char 1 to -2 of pColsToReturnExpanded into pColsToReturn
>   if pDelim = empty then put tab into pDelim
>   set the columnDelimiter to pDelim
>   split pData by column
>   put item 2 of extents(pData) into tMax
>   repeat for each item n in pColsToReturn
>         add 1 to x
>         put pData[n] into rData[x]
>   end repeat
>   combine rData by column
> return rData
> end extractColumns
> 
> 
> On Sep 5, 2014, at 1:51 PM, Michael Doub <mikedoub at gmail.com> wrote:
> 
>> Here is an even more general version:
>> 
>> function deleteColumns pData,pColsToDelete,pDelim
>>  -- delete specified columns from a table
>>  -- Syntax: deleteColumns <data>,<cols>[,<delim>]
>>  --     data: Specifies the data to parse.
>>  --     cols: A comma separated list of columns or column ranges to be removed,
>>  --         for example "2,5,7"
>>  --         or a column range: "3-5"
>>  --         or a combination "2,4-5,7,9-11,"
>>  --     delim: Optional column separator for example "," or "|"
>>  --         if unspecified, defaults to tab.
>>  -- based on a handler by Hugh Senior and Peter M. Brigham, Use-LC list
>> 
>>  -- requires getItem()
>> 
>>  if pColsToDelete = empty then return pData
>>  repeat for each item pCol in pColsToDelete
>>     if "-" is in pCol then 
>>        put getItem(pCol,1,"-") into firstColNbr
>>        put getItem(pCol,2,"-") into lastColNbr
>>        repeat with i = firstColNbr to lastColNbr
>>           put i & comma after pColsToDeleteExpanded
>>        end repeat
>>     else
>>        put pCol & comma after pColsToDeleteExpanded
>>     end if
>>  end repeat
>>  put char 1 to -2 of pColsToDeleteExpanded into pColsToDelete
>>  if pDelim = empty then put tab into pDelim
>>  set the columnDelimiter to pDelim
>>  split pData by column
>>  put item 2 of extents(pData) into tMax
>>  repeat with n=1 to tMax
>>     if n is NOT among the items of pColsToDelete then
>>        add 1 to x
>>        put pData[n] into pData[x]
>>     end if
>>  end repeat
>>  repeat with n=x+1 to tMax
>>     delete local pData[n]
>>  end repeat
>>  combine pData by column
>>  return pData
>> end deleteColumns
>> 
>> function getItem tList,tIndex,tDelim
>>  -- returns item # tIndex of tList, given itemdelimiter = tDelim
>>  -- could just "get item tIndex of tList" in the calling handler but
>>  --    then have to set and restore the itemDelimiter, so this is less hassle
>>  -- defaults to tDelim = comma
>> 
>>  if tDelim = empty then put comma into tDelim
>>  set the itemdelimiter to tDelim
>>  return item tIndex of tList
>> end getItem
>> 
>> 
>> 
>> On Sep 5, 2014, at 10:58 AM, Peter M. Brigham <pmbrig at gmail.com> wrote:
>> 
>>> Peter M. Brigham
>> 
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