R/extract.R
extract.RdThe surveydata package makes it easy to extract specific questions from a surveydata object. Because survey data typically has question names like "Q1_a", "Q1_b", "Q1_c" the extract method for a surveydata object makes it easy to extract all columns by simply specifying "Q1" as the argument to the column index.
# S3 method for surveydata
[(x, i, j, drop = FALSE)
# S3 method for surveydata
[(x, i, j) <- value
# S3 method for surveydata
$(x, name) <- valuesurveydata object
row index
column index
logical. Passed to [.data.frame. Note that the default is FALSE.
New value
Names of columns
Extraction is similar to data frames, with three important exceptions:
The column argument j is evaluated using which.q() and will return all columns where the column names match the pattern().
The drop argument is FALSE. Thus the result will always be a surveydata object, even if only a single column is returned.
All extraction methods retain the pattern and varlabels arguments.
names(membersurvey)
#> [1] "id" "Q1_1" "Q1_2" "Q2" "Q3_1" "Q3_2"
#> [7] "Q3_3" "Q3_4" "Q3_5" "Q3_6" "Q3_7" "Q3_8"
#> [13] "Q3_9" "Q3_10" "Q3_11" "Q3_12" "Q3_13" "Q3_14"
#> [19] "Q3_15" "Q4" "Q5" "Q6_1" "Q6_2" "Q6_3"
#> [25] "Q6_4" "Q6_5" "Q6_6" "Q6_7" "Q6_8" "Q6_9"
#> [31] "Q6_10" "Q7" "Q8" "Q9_1" "Q9_2" "Q9_3"
#> [37] "Q9_4" "Q9_5" "Q10" "Q11_1" "Q11_2" "Q11_3"
#> [43] "Q11_4" "Q11_5" "Q11_other" "Q12_1" "Q13_1" "Q13_2"
#> [49] "Q13_3" "Q13_4" "Q14_1" "Q14_2" "Q14_3" "Q14_4"
#> [55] "Q14_5" "Q14_6" "Q14_7" "Q14_8" "Q14_9" "Q14_10"
#> [61] "Q15_1" "Q15_2" "Q15_3" "Q15_4" "Q15_5" "Q15_6"
#> [67] "Q19_1" "Q19_2" "Q19_3" "Q19_4" "Q19_5" "Q19_6"
#> [73] "Q20_1" "Q20_2" "Q20_3" "Q20_4" "Q20_5" "Q20_6"
#> [79] "Q20_7" "Q20_8" "Q20_9" "Q20_10" "Q20_other" "Q21_1"
#> [85] "Q21_2" "Q21_3" "Q21_4" "Q21_5" "Q21_6" "Q23_1"
#> [91] "Q23_2" "Q23_3" "Q23_4" "Q23_5" "Q23_other" "Q24"
#> [97] "Q25" "Q26_1" "Q27_1" "Q27_2" "Q30" "Q30_other"
#> [103] "Q31" "Q31_other" "Q32" "Q33" "Q35" "weight"
#> [109] "size"
head(membersurvey["Q1"])
#> Q1_1 Q1_2
#> 1 8 2
#> 2 35 12
#> 3 34 12
#> 4 20 9
#> 5 20 3
#> 6 36 20
head(membersurvey[c("Q1", "Q2")])
#> Q1_1 Q1_2 Q2
#> 1 8 2 2009
#> 2 35 12 Before 2002
#> 3 34 12 Before 2002
#> 4 20 9 2010
#> 5 20 3 2010
#> 6 36 20 Before 2002
head(membersurvey[membersurvey$Q2=="2009", c("Q1", "Q2")])
#> Q1_1 Q1_2 Q2
#> 1 8 2.0 2009
#> 7 12 2.5 2009
#> 16 20 5.0 2009
#> 37 25 2.0 2009
#> 51 7 2.5 2009
#> 65 7 20.0 2009
# The pattern is used to extract columns
pattern(membersurvey)
#> $sep
#> [1] "_"
#>
#> $exclude
#> [1] "other"
#>
grep("Q20", names(membersurvey), value=TRUE)
#> [1] "Q20_1" "Q20_2" "Q20_3" "Q20_4" "Q20_5" "Q20_6"
#> [7] "Q20_7" "Q20_8" "Q20_9" "Q20_10" "Q20_other"
head(membersurvey["Q20"])
#> Q20_1 Q20_2 Q20_3 Q20_4 Q20_5 Q20_6 Q20_7 Q20_8 Q20_9 Q20_10
#> 1 Yes No No No No No No No No No
#> 2 No No No No No No No No No No
#> 3 No No No No No No No No No No
#> 4 Yes Yes No No No No No No No Yes
#> 5 No No No No No No No No No No
#> 6 No Yes No Yes Yes No No No No No
head(membersurvey["Q20_other"])
#> Q20_other
#> 1 <NA>
#> 2 <NA>
#> 3 <NA>
#> 4 <NA>
#> 5 I rarely attend business events in the evening
#> 6 <NA>