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| From | wyldsoul <wyldsoul@gmail.com> |
|---|---|
| Newsgroups | comp.soft-sys.sas |
| Subject | interpolating missing values |
| Date | 2011-06-20 13:25 -0700 |
| Organization | http://groups.google.com |
| Message-ID | <4be0f2da-c05f-40ba-95a7-cda03c9e3854@s16g2000prf.googlegroups.com> (permalink) |
Hi all, I want to interpolate missing values from gage data. This is easy to do manually in excel, however, I have over 60 years of water level data from dozens of stage gages, and would like to find a way to batch interpolate in SAS. In order to interpolate, for each set of missing values I need to calculate the difference between the last observation before the first blank value and the first observation after the last blank value. Then divide the result of this by the total number of missing values+1. Simply put: (first obs± last obs)/(# missing obs+1) or using the sample data from below: (6.05-6.01)/4=0.01 Then I need to populate each missing observation by cumulatively adding or subtracting the result of the previous calculation to each successive blank until you reach the next non-blank observation. The sample dataset is below. Stage is the original value, int_factor is the result of the first calculation, and interp_stage is the interpolated stage based on cumulatively adding the int_factor to each observation . Station date stage int_factor interp_stage NP-P33 1-Jan-53 6.04 6.04 NP-P33 2-Jan-53 6.03 6.03 NP-P33 3-Jan-53 6.02 6.02 NP-P33 4-Jan-53 6.01 6.01 NP-P33 5-Jan-53 0.0100 6.02 NP-P33 6-Jan-53 6.03 NP-P33 7-Jan-53 6.04 NP-P33 8-Jan-53 6.05 6.05 NP-P33 9-Jan-53 6.15 6.15 NP-P33 10-Jan-53 6.20 6.2 NP-P33 11-Jan-53 6.20 6.2 NP-P33 12-Jan-53 6.19 6.19 NP-P33 13-Jan-53 6.18 6.18 NP-P33 14-Jan-53 6.17 6.17 NP-P33 15-Jan-53 6.16 6.16 NP-P33 16-Jan-53 6.15 6.15 NP-P33 17-Jan-53 6.14 6.14 NP-P33 18-Jan-53 6.13 6.13 NP-P33 19-Jan-53 6.12 6.12 NP-P33 20-Jan-53 0.0091 6.11 NP-P33 21-Jan-53 6.10 NP-P33 22-Jan-53 6.09 NP-P33 23-Jan-53 6.08 NP-P33 24-Jan-53 6.07 NP-P33 25-Jan-53 6.07 NP-P33 26-Jan-53 6.06 NP-P33 27-Jan-53 6.05 NP-P33 28-Jan-53 6.04 NP-P33 29-Jan-53 6.03 NP-P33 30-Jan-53 6.02 6.02 NP-P33 31-Jan-53 6.02 6.02
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interpolating missing values wyldsoul <wyldsoul@gmail.com> - 2011-06-20 13:25 -0700
Re: interpolating missing values "Kenneth M. Lin" <kenneth_m_lin@sbcglobal.net> - 2011-06-20 15:22 -0700
Re: interpolating missing values wyldsoul <wyldsoul@gmail.com> - 2011-06-21 07:03 -0700
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