3.38 mnullto - Replace NULL Values

Replace NULL values in the field(s) specified at f= parameter with a character string defined at v= parameter.

Format

mnullto f= [v=|-p] [O=] [-A] [i=] [o=] [-nfn] [-nfno] [-x] [--help] [--version]

Parameters

`f=`	Replace null values in the field(s) (multiple fields can be specified).
`v=`	Replace null values with this string.
`-p`	Replace null values in the previous row.
	This option cannot be specified with `v=` parameter.
`O=`	String to replace non-null values.
	When this parameter is not specified, non-null values will not be replaced.
`-A`	Add replacement string as new column.
	When `-A` option is specified, define the new field name using a colon (:) after the field name.
	Example: f=quantity:ReplacementFieldName.

Examples

Example 1: Basic Example

Replace NULL values in the ¥verb|birthday| field with the string “no value”.

$ more dat1.csv
customer,birthday
A,19690103
B,
C,19500501
D,
E,
$ mnullto f=birthday v="no value" i=dat1.csv o=rsl1.csv
#END# kgnullto f=birthday i=dat1.csv o=rsl1.csv v=no value
$ more rsl1.csv
customer,birthday
A,19690103
B,no value
C,19500501
D,no value
E,no value

Example 2: Replace non-NULL values

Replace Null values in the birthday field with the string "no value" and change non-null values to the string ¥verb|"value"|, and rename the output column as entry.

$ mnullto f=birthday:entry v="no value" O="value" i=dat1.csv o=rsl2.csv
#END# kgnullto O=value f=birthday:entry i=dat1.csv o=rsl2.csv v=no value
$ more rsl2.csv
customer,entry
A,value
B,no value
C,value
D,no value
E,no value

Example 3: Add new column

Replace Null values in the birthday field with the string "no value" and change non-null values to the string "value". Output the replacement strings in a new column named entry.

$ mnullto f=birthday:entry v="no value" O="value" -A i=dat1.csv o=rsl3.csv
#END# kgnullto -A O=value f=birthday:entry i=dat1.csv o=rsl3.csv v=no value
$ more rsl3.csv
customer,birthday,entry
A,19690103,value
B,,no value
C,19500501,value
D,,no value
E,,no value

Example 4: Replace values in previous row

$ more dat2.csv
id,date
A,19690103
B,
C,19500501
D,
E,
$ mnullto f=date -p i=dat2.csv o=rsl4.csv
#END# kgnullto -p f=date i=dat2.csv o=rsl4.csv
$ more rsl4.csv
id,date
A,19690103
B,19690103
C,19500501
D,19500501
E,19500501

Related Commands

mdelnull : Remove rows containing NULL values.

mchgstr : Replace NULL value with character strings.