What’s wrong NOW?! An introduction to debugging SAS programs for beginners Martha Cox Cancer Outcomes Research Program CDHA / Dalhousie

1
Whats wrong NOW?!An introduction to debugging
SAS programs for beginnersMartha CoxCancer
Outcomes Research ProgramCDHA / Dalhousie
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Whats wrong NOW?!

• Types of Bugs
• Bug Droppings
• Bug Repellant
• Bug Killing General Approach
• Bug Killing Specific Bugs

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Types of Bugs

• Syntax / Semantic

4
Types of Bugs

• Syntax / Semantic
• Execution-Time

5
Types of Bugs

• Syntax / Semantic
• Execution-Time
• Data

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Types of Bugs

• Syntax / Semantic
• Execution-Time
• Data
• Logic

7
Bug Droppings

• ERROR
• WARNING
• NOTE
• no messages

8
Bug Repellant

• Make your program easy to read

• Indent within a step or a DO block
• One Semicolon per Line (or less!)
• Every step gets a RUN
• Every PROC gets a DATA
• Comments, comments, comments

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Make your program easy to read

• data hyst
• set hospital(keepyear pcode1-pcode10)
• array pcodes pcode1-pcode10
• length code 3 year 3
• do i 1 to 10
• if pcodesi'689 then do
• code substr(pcodesi,1,3)
• output end end keep year code
• title1 'Number of Selected Hysterectomy
  Procedures by Year'
• proc freq noprint tables yearcode/list
  outtemp
• run

10

• / Create a data set containing hysterectomy
  codes. /
• data hyst
• set hospital
• (keepyear pcode1-pcode10)
• array pcodes pcode1-pcode10
• length code 3
• year 3
• do i 1 to 10
• if pcodesi '689
• then do
• code substr(pcodesi,1,3)
• output
• end if
• end do i
• keep year code
• run
• title1 'Number of Selected Hysterectomy
  Procedures by Year'

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Bug Repellant

• Make your program easy to read
• Dont destroy your data

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Dont Destroy Your Dataaccessreadonly

• libname survey 'C\My Documents\Survey\'
  accessreadonly
• libname indata 'C\Thesis\Data\'
  accessreadonly
• libname outdata 'C\Thesis\Data\'

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Dont Destroy Your DataUse OUT on PROC SORT

• proc sort datathesis.hospital
• (keeppatient addate)
• by patient
• run
• proc sort datathesis.hospital
• (keeppatient addate)
• outpatlist
• by patient
• run

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Dont Destroy Your Dataoptions DATASTMTCHK

• 7 options datastmtchknone
• 8 data adults
• 9 set survey.adult
• 10 if age gt 65
• 11 run
• NOTE Variable age is uninitialized.
• NOTE The SAS System stopped processing this step
  because of errors.
• WARNING The data set WORK.ADULTS may be
  incomplete. When this step was stopped there
  were 0 observations and 1 variables.

15
Dont Destroy Your Dataoptions DATASTMTCHK

• 12 options datastmtchkcorekeywords
• 13 data adults
• NOTE SCL source line.
• 14 set survey.adult
• ---
• 56
• ERROR 56-185 SET is not allowed in the DATA
  statement when option DATASTMTCHKCOREKEYWORDS.
  Check for a missing semicolon in the DATA
  statement, or use DATASTMTCHKNONE.
• 15 if age gt 65
• 16 run

16
Dont Destroy Your Dataoptions MERGENOBY

• 13 data valid not_valid
• 14 merge TEST_DATA(keepID ina)
• 15 master.master02(inb)
• 18 if a and b then output valid
• 19 else if not b then output
  not_valid
• 20 run
• NOTE There were 899 observations read from the
  data set TEST_DATA.
• NOTE There were 1138309 observations read from
  the data set MASTER.MASTER02.
• NOTE The data set WORK.VALID has 899
  observations and 9 variables.
• NOTE The data set WORK.NOT_VALID has 0
  observations and 9 variables.

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Dont Destroy Your Dataoptions MERGENOBY

• 12 options mergenobyerror
• 13 data valid not_valid
• 14 merge TEST_DATA(keepID ina)
• 16 master.master02(inb)
• 17 if a and b then output valid
• 18 else if not b then output not_valid
• 19 run
• ERROR No BY statement was specified for a MERGE
  statement.
• NOTE The SAS System stopped processing this
  step because of errors.

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Bug Repellant

• Make your program ( your log) easy to read
• Dont destroy your data
• Know your data

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Know your data

• 21 data males
• 22 set survey.adult
• 23 if gender 'M'
• 24 run
• NOTE Character values have been converted to
  numeric values at the places given by
  (Line)(Column).
• 2312
• NOTE Invalid numeric data, 'M' , at line 23
  column 12.

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Bug Repellant

• Make your program ( your log) easy to read
• Dont destroy your data
• Know your data
• Do a syntax check

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Do a syntax check

• options OBS0 NOREPLACE

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Bug Repellant

• Make your program ( your log) easy to read
• Dont destroy your data
• Know your data
• Do a syntax check

23
Bug Killing

• Read the LOG!

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Bug Killing

• Start at the top deal with one mess at a time.

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Bug Killing

• Start at the top deal with one mess at a time.

• Use interactive SAS, if possible

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Bug Killing

• Start at the top deal with one mess at a time.

• Use interactive SAS, if possible
• Using ENDSAS

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Using ENDSAS

• lt lots of SAS statements gt
• proc freq dataworkhrs
• tables hrs / nofreq nocum norow
• run
• endsas
• lt lots more SAS statements gt

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Bug Killing

• Start at the top deal with one mess at a time.

• Use interactive SAS, if possible
• Using ENDSAS
• Using OPTIONS ERRORABEND

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Using ERRORABEND

• 1 options errorabend
• 5 / Number of Hours Worked Per Week /
• 6 data workhrs(dropb151)
• 7 set survey.newadult
• 8 (keepwrk)
• ERROR The variable wrk in the DROP, KEEP, or
  RENAME list has never been referenced.
• 9 length hrs 8
• 10 hrs input(b151, 8.)
• 11 run
• ERROR SAS ended due to errors.
• You specified OPTIONS ERRORABEND.

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Bug Killing

• Look for horses, not zebras.

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Bug Killing

• Read the LOG!
• Start at the top deal with one mess at a time.
• Look for horses, not zebras.

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Bug Killing

• Some Specific Bugs

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WARNING or ERRORmisspelled keywords

• 33 data adult
• NOTE SCL source line.
• 34 st aborig.newadult
• --
• 1
• WARNING 1-322 Assuming the symbol SET was
  misspelled as st.
• 35 run

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ERROR Invalid option name, parameter, or
statement.

• Possible Causes
• missing semicolon
• misspelled keyword
• unmatched quotation mark
• unclosed comment
• a DATA step statement in a PROC step
• a valid option used in the wrong place

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ERROR Invalid option name, parameter, or
statement.

• 3 data males(ropgender)
• ---
• 22
• ERROR 22-7 Invalid option name ROP.
• 4 set survey.adult
• 5 if gender 2
• 6 run
• NOTE The SAS System stopped processing this step
  because of errors.

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ERROR Invalid option name, parameter, or
statement.

• 8 proc print datasurvey.adult
• NOTE SCL source line.
• 9 set gender
• ---
• 180
• ERROR 180-322 Statement is not valid or it is
  used out of proper order.
• 10 run
• NOTE The SAS System stopped processing this step
  because of errors.

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ERROR Invalid option name, parameter, or
statement.

• 11 proc print datasurvey.adult
• NOTE SCL source line.
• 12 var gender
• --- --
• 22 202
• ERROR 22-322 Syntax error, expecting one of the
  following , (, DATA, DOUBLE, HEADING, LABEL, N,
  NOOBS, OBS, ROUND, ROWS, SPLIT, STYLE, UNIFORM,
  WIDTH.
• ERROR 202-322 The option or parameter is not
  recognized and will be ignored.
• 13 run
• NOTE The SAS System stopped processing this step
  because of errors.

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ERROR Invalid option name, parameter, or
statement.

• 14 Print a list of Adult ages.
• 15 proc print datasurvey.newadult
• NOTE SCL source line.
• 16 var b4
• ---
• 180
• ERROR 180-322 Statement is not valid or it is
  used out of proper order.
• 17 run

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WARNING unbalanced quotes

• 90 proc print datahospital(obs10)
• 91 title1 "Sample of Hospital Data
• 92 run
• 93
• lt more SAS statements gt
• 91 title1 "Sample of Hospital Data
• _____________________
• _____________________
• _____________________
• 32
• 32
• 32
• WARNING 32-169 The quoted string currently
  being processed has become more than 262
  characters long. You may have unbalanced
  quotation marks.

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NOTE Missing values generated.

• 48 data test
• 49 a 2 b 4 c .
• 50 x a b c
• 51 y sum(a,b,c)
• 52 a . b .
• 53 z sum(a,b,c)
• 54 z2 sum(a,b,c,0)
• 55 put x y z z2
• 56 run
• x. y6 z. z20
• NOTE Missing values were generated as a result
  of performing an operation on missing values.
  Each place is given by (Number of times) at
  (Line)(Column).
• 1 at 5013 1 at 537

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NOTE Numeric to character conversion (or vice
versa)

• 109 data adult2
• 110 length sexage 5 household 8
• 111 set adult
• 112 sexage sex age
• 113 household sum(kids, adults, 1)
• 114 run
• NOTE Numeric values have been converted to
  character
• values at the places given by
  (Line)(Column).
• 11219
• NOTE Character values have been converted to
  numeric
• values at the places given by
  (Line)(Column).
• 11319

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NOTE Numeric to character conversion (or vice
versa)

• 122 data adult3
• 123 length sexage 5 household 8
• 124 set adult
• 125 sexage sex put(age, 3. -L)
• 126 kidsnum input(kids, 8.)
• 127 household sum(kidsnum, adults, 1)
• 128 run
• NOTE There were 493 observations read from the
  data set WORK.ADULT.
• NOTE The data set WORK.ADULT3 has 493
  observations and 8 variables.

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NOTE Variable is uninitialized.

• Possible Causes
• misspelling the variable name
• using a variable that was dropped in a previous
  step
• using the wrong data set
• using a variable before it is created

44
NOTE Variable is uninitialized.

• 140 data males
• 141 set survey.adult
• 142 (keepid community)
• 143 if gender2
• 144 run
• NOTE Variable gender is uninitialized.
• NOTE There were 493 observations read from the
  data set SURVEY.ADULT.
• NOTE The data set WORK.MALES has 0 observations
  and 3 variables.

45
No Messages Character values are being truncated.

• data groups
• set survey.adult
• if age lt 20 then AgeGroup 'Teen'
• else if age gt 65 then AgeGroup 'Senior'
• else AgeGroup 'Adult'
• run
• proc freq datagroups
• tables agegroup / nocum
• run

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No Messages Character values are being truncated.

• The FREQ Procedure
• Age
• Group Frequency Percent
• ------------------------------
• Adul 388 78.70
• Seni 17 3.45
• Teen 88 17.85

47
No Messages Character values are being truncated.

• data groups
• set survey.adult
• attrib AgeGroup length6 label'Age Group'
• if age lt 20 then AgeGroup 'Teen'
• else if age gt 65 then AgeGroup 'Senior'
• else AgeGroup 'Adult'
• run
• proc freq datagroups
• tables agegroup / nocum
• run

48
No Messages Character values are being truncated.

• The FREQ Procedure
• Age
• Group Frequency Percent
• -------------------------------
• Adult 388 78.70
• Senior 17 3.45
• Teen 88 17.85

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Questions?
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References

• Delwiche, Lora D., and Susan J. Slaughter, The
  Little SAS Book a primer, Third Edition, SAS
  Institute, Cary, NC, 2003
• Staum, Roger, To Err is Human to Debug Divine,
  NESUG 15 Conference Proceedings
• Howard, Neil, How SAS Thinks, or Why the DATA
  Step Does What It Does, SUGI 29 Conference
  Proceedings
• Knapp, Peter, Debugging 101, NESUG 15 Conference
  Proceedings
• Rhodes, Dianne Louise, So You Want to Write a
  SUGI Paper? That Paper About Writing a Paper,
  SUGI 29 Conference Proceedings

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Resources

• Online documentation http//v9doc.sas.com/sa
  sdoc/
• Online conference proceedings
• SUGI http//support.sas.com/usergroups/
  sugi/proceedings/index.html
• NESUG http//www.nesug.org/