findgroups
Find groups and return group numbers
Syntax
Description
To split data into groups and apply a function to the groups, use the
findgroups
and splitapply
functions
together. For more information about calculations on groups of data, see Calculations on Groups of Data.
returns
G
= findgroups(A
)G
, a vector of group numbers created from the grouping
variable A
. The output argument G
contains
integer values from 1 to N
, indicating N
distinct groups for the N
unique values in
A
. For example, if A
is
["b","a","a","b"]
, then findgroups
returns G
as [2 1 1 2]
.
To use G
to split groups of data out of other variables,
pass it as an input argument to the splitapply
function.
The findgroups
function treats empty character vectors and
NaN
, NaT
, and undefined categorical
values in A
as missing values and returns
NaN
as the corresponding elements of
G
.
creates group numbers from G
= findgroups(A
1,...,A
N)A1,...,AN
. The
findgroups
function defines groups as the unique
combinations of values across A1,...,AN
. For example, if
A1
is ["a","a","b","b"]
and
A2
is [0 1 0 0]
, then
findgroups(A1,A2)
returns G
as
[1 2 3 3]
, because the combination "b"
0
occurs twice.
[
also returns the unique values for each group across
G
,ID
1,...,ID
N] = findgroups(A
1,...,A
N)ID1,...,IDN
. The values across
ID1,...,IDN
define the groups. For example, if
A1
is ["a","a","b","b"]
and
A2
is [0 1 0 0]
, then
findgroups(A1,A2)
returns G
as
[1 2 3 3]
, and ID1
and
ID2
as ["a","a","b"]
and [0 1
0]
.
Examples
Input Arguments
Output Arguments
More About
Extended Capabilities
Version History
Introduced in R2015b
See Also
splitapply
| pivot
| unique
| ismember
| rowfun
| varfun
| arrayfun
| groupsummary
| discretize
| histcounts
| accumarray
| convertvars
| vartype