[Pharo-users] NeoCSV and special handling for some columns

stepharo stepharo at free.fr
Sat Oct 3 02:54:10 EDT 2015


sven do you think that we should add this to the chapter?


Le 28/9/15 16:42, Sven Van Caekenberghe a écrit :
>> On 28 Sep 2015, at 15:04, Mariano Martinez Peck <marianopeck at gmail.com> wrote:
>>
>> Imagine something like this:
>>
>> neoCSVReader := (NeoCSVReader on: stream).
>> 	neoCSVReader
>> 		separator: $,;
>> 		recordClass: PriceRecord;
>> 	 	addIgnoredField; "<name>"
>> 		addField:  #securityUniqueId: ; "<ticker>"	
>> 		addField: #date: converter: [ :string | Date readFrom: string readStream pattern: 'yyyymmdd' ]; "<date>"
>> 		addFloatField: #open: ; "<open>"
>> 		addFloatField: #high: ; "<high>"
>> 		addFloatField: #low: ; "<low>"
>> 		addFloatField: #close: ; "<close>"
>> 		addIntegerField: #volume: . "<vol>"
>> 	neoCSVReader	skipHeader.
>> 	priceRecords := neoCSVReader upToEnd.
>>
>>
>> The #recordClass: is optional. If not, you can get an array of arrays instead.
>> You can add #addIgnoredField for all the ones you want to ignore, then add the #addNumber: etc for the number ones, etc.
> Correct.
>
>> To write a default empty value, I would use my own converter. Something like:
>>
>> addField: #stringcolumn: converter: [ :string | string isEmptyOrNil ifTrue: [ '' ]  ];
>> addField: #numbercolumn: converter: [ :string | string isEmptyOrNil ifTrue: [ 0 ] ifFalse: [ NeoNumberParser parse: string ]  ];
> Actually there is NeoCSVReader>>#emptyFieldValue: which you can use the configure the reader (but it counts for all fields).
>
>> Hope this helps.
>>
>> Cheers,
>>
>>
>>
>> On Mon, Sep 28, 2015 at 9:06 AM, Nicolai Hess <nicolaihess at web.de> wrote:
>> Hi,
>>
>> I have two problems I could not solve:
>>
>> 1. I would like to read only some columns: I have a large file with
>>      ~30 colums, but I am only interested on ~5 columns
>>      (not that important, I could pre-process the file) but anyway it would be
>>      nice to do it in smalltalk.
>>
>> 2. some columns will contain only strings (quoted values) and some only numbers,
>>      but the field may be empty, is it possible to define the default "emptyValue" as an
>>      - empty string for empty fields in the "string column"
>>      - 0 for empty fields in the "number column"?
>>
>>
>> thanks
>>   in advance
>>
>> nicolai
>>
>>
>>
>> -- 
>> Mariano
>> http://marianopeck.wordpress.com
>
>





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