Missing Values

Missing values are represented by the symbol 'na. Only the exact symbol 'na is treated as missing — "na" (string), 'NA, and other variants are not.

(na? obj)

returns: #t if obj is 'na, #f otherwise.

(any-na? lst)

returns: #t if any element of lst is 'na, #f otherwise.

> (na? 'na)
#t
> (na? "na")
#f
> (na? 'NA)
#f
> (any-na? (iota 10))
#f
> (any-na? (cons 'na (iota 10)))
#t
> (any-na? (cons "na" (iota 10)))
#f

---

(remove-na lst)

returns: lst with all 'na elements removed.

> (remove-na '(1 na 2 3))
(1 2 3)
> (remove-na '(1 NA 2 3))   ; 'NA is not missing
(1 NA 2 3)
> (remove-na '(1 "na" 2 3)) ; "na" is not missing
(1 "na" 2 3)

---

(dataframe-remove-na df [name ...])

returns: a dataframe with rows containing 'na removed. By default removes rows where any column is 'na. Optionally restrict to specific column names.

> (define df
    (make-df*
      (a 1 2 3 4 'na)
      (b 'na 7 8 9 10)
      (c 11 12 'na 14 15)))

> (dataframe-display (dataframe-remove-na df))

 dim: 2 rows x 3 cols
       a       b       c
   <num>   <num>   <num>
      2.      7.     12.
      4.      9.     14.

;; Remove rows where only columns a or c are na
> (dataframe-display (dataframe-remove-na df 'a 'c))

 dim: 3 rows x 3 cols
       a       b       c
   <num>   <num>   <num>
      1.      na     11.
      2.       7     12.
      4.       9     14.