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233:mg_copy_subfield [2013/04/27 09:09] (current)
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 +**Using the 'Copy Subfield' task in MARC Global**
 +
 +We've made a few changes to how 'Copy Subfield' works in the current version. 
 +
 +First, when selecting the 'Move subfield' option in 232, the program would move the whole field instead of just the specified subfield. This problem is fixed in 233.
 +
 +In addition to this fix, we've enhanced the capability of 'Copy Subfield' in 233, adding three new possibilities to the standard use of this task.
 +
 +__Copying only a portion of a subfield__
 +
 +First, its now possible to select a substring within a subfield for copying. There are two ways to do this: 
 +  - By specifying the offset and length within the subfield of the substring to be copied
 +  - By specifying a pattern to match the beginning of the substring to be copied
 +
 +To use this technique, proceed as follows: Enter the Tag and Subfield to Copy From on the 'Copy Subfield' form, then right-click on the 'Subf' box. The following form will pop-up:
 +
 +{{:233:copy_substring.jpg|}}
 +
 +If you are working with fairly fixed data, you can use the 'Start At' field to enter the position--within the subfield--to begin copying from, and then use the 'Length' field to enter the number of bytes to copy. Leave 'Length' set to 0 to copy all remaining bytes in the subfield. The example above will copy only the first four bytes from wahtever subfield is specified.
 +
 +On the other hand, a pattern can also be entered in the 'Start At' field. The case-sensitive and regular expression options available in standard patterns are also supported here. The 'Length' field works as above; leave it to '0' to copy all remaining bytes, or set it to a number to copy only that many bytes from the point where the pattern matches.
 +
 +We recently found this new option useful to copy all of the document IDs from a URL field into a separate tag (which was then used to match/merge/update records). For example, the source data looked like this;
 + 
 +  856 40 $uhttp://web.lib.com/eBooks?docId=CX3477199999$zClick here to access.
 +
 +By using the 'Copy Subfield' + Pattern option--
 +
 +{{:233:copy_subf_pattern.jpg|}}
 +
 +--we were able to generate a control number in each record that contained only the 'docID' portion of the 856 $u:
 +
 +  035 $aCX3477199999
 +
 +
 +__Copying one subfield to many tags__
 +
 +Second, its now possible in 233 to copy a specified subfield to all occurrences of a target tag. For example, to copy the first 049$a in a record to a $z in all occurences of a 949 field, we would use the following 'Copy Subfield' options:
 +
 +{{:233:copy_one_subf_to_many.jpg|}}
 +
 +Thus, if the source record contains
 +
 +  049  $aMyCode
 +  949  $aData$bMoreData
 +  949  $aData$bMoreData
 +  949  $aData$bMoreData
 +
 +the result of performing the above Copy Subfield task on this record would be
 +
 +  049  $aMyCode
 +  949  $aData$bMoreData$zMyCode
 +  949  $aData$bMoreData$zMyCode
 +  949  $aData$bMoreData$zMyCode
 +
 +__Copying many subfields to one tag__
 +
 +Third, it is also possible in 233 to copy each occurrences of a subfield in a tag that repeats, to a new subfield in a single target tag. For example, to copy each $a subfield in a 949 tag to a new $z in a 999 tag, we would use the following options:
 +
 +{{:233:copy_subf_all_to_one.jpg|}}
 +
 +Thus, if the source record contains
 +
 +  949  $aData1
 +  949  $aData2
 +  949  $aData3
 +
 +the result of performing the above Copy Subfield task on this record would be
 +
 +  949  $aData1
 +  949  $aData2
 +  949  $aData3
 +  999  $zData1$zData2$zData3
 +
 +For this to work, its important that the overlay option be set to 'Add new subf'; if it is set to 'Replace subfield' then each $z added to the 999 will overwrite the previous one, and the above result would look like:
 +
 +  949  $aData1
 +  949  $aData2
 +  949  $aData3
 +  999  $zData3
 +
 +One limitation to this second type of 'Copy Subfield' is that it will not work as expected if the subfields to be copied are repeated __within__ a field. For example, if the source record contains 
 +
 +  949  $aData1$aData2$aData3
 +
 +the result of performing the same Copy Subfield task on this record would be
 +
 +  949  $aData1$aData2$aData3
 +  999  $aData1
 +  
 +The program will only pick up the first $a in the source tag (even if you select the 'All' occurrence option). The desired result here is probably
 +
 +  949  $aData1$aData2$aData3
 +  999  $aData1$aData2$aData3
 +
 +Hopefully we can improve this behavior in a future version.
 +
 +
 +
 +
 +
 +
 +
  
233/mg_copy_subfield.txt · Last modified: 2013/04/27 09:09 (external edit)
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