I want it to know how to convert string field values to integer values in QGIS Dufour... there are numbers and strings in the same field, when I use toreal(string) it stops and it won´t create the field.


I just tried to convert a string to an integer in QGIS Dufour with no issues. I had a text string that was 7 characters long. I did the following:

  • Create a new field (temp2) that is a whole number and holds 10 characters (longer than my source)
  • Field calculate temp2 with: toreal( "temp1" )
  • Field calculate temp3 with: toint( "temp1" )

Both examples worked and produced numbers from text. Make sure you only have numeric values in the source field. If you have any alpha values (a - z) or special characters (* # $ _ etc.) the conversion will not work. The source field must only contain numeric values (0 -9)

  • Dear Ryan, that is the point, I have GPS data, some are numbers, others are descriptive string in the same field, I just want the numbers – Carlos Rivas Oct 21 '13 at 19:40
  • Well, sometimes the answer is in your question... I will just select the values that I want to be converted! Works perfectly! – Carlos Rivas Oct 21 '13 at 19:42
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    Carlos, are the GPS values uniform? What I mean is do they follow a pattern? In the example I had a text string that was hal1000000, hal1000001, hal1000002....What I did was to do a substr( "BLDGID" , 4, 7) This takes the source text field and chops out only the number values (starting at the 4th place and counting 7 values out). Here is a conversion to do it all in one. If you have number values in between letters you may need to be creative with the starting and ending numbers, or do it in two steps. – Ryan Garnett Oct 21 '13 at 19:56
  • Ryan, I just sort by name then select the first ones (who has numbers) then use the field calculator and done!.. problema resuelto amigo. Gracias! – Carlos Rivas Oct 21 '13 at 20:26
  • Glad you got it figured out. – Ryan Garnett Oct 21 '13 at 20:34

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