IMSTAT Procedure (Analytics)

SUMMARY Statement

The SUMMARY statement is used to calculate descriptive statistics such as the sample mean, sample variance, number of observations, sum of squares, and so on. If you specify one or more variables in the GROUPBY= option, the results are produced separately for each combination of the GROUPBY variables.

Partitioning a Table into a Temporary Table

Deleting Rows and Saving a Table to HDFS

Syntax

SUMMARY <variable-list> </ options>;

Optional Argument

variable-list

specifies one or more numeric variables. If you do not specify this option, then all numeric variables in the table are used.

SUMMARY Statement Options

AGGREGATE=(aggregation-methods)

lists the aggregator on which the ordering of the result set is based.

The available aggregation methods are as follows:
CSS corrected sum of squares
CV coefficient of variation
MAX maximum value
MEAN arithmetic mean
MIN minimum value
N number of observations
NMISS number of missing observations
PROBT p-value for the t-statistic
STD standard deviation
STDERR standard error
SUM sum of the nonmissing values
TSTAT t-statistic for the null hypothesis that the mean equals zero
USS uncorrected sum of squares
VAR sample variance
Alias AGG=

DESCENDING

specifies that the levels of the GROUPBY variables are to be arranged in descending order.

Alias DESC

FORMATS=("format-specification",...)

specifies the formats for the GROUPBY= variables. If you do not specify the FORMATS= option, or if you omit the entry for a GROUPBY variable, the default format is applied for that variable.

Enclose each format specification in quotation marks and separate each format specification with a comma.
Example
proc imstat data=lasr1.table1;
   summary x*y / groupby=(a b) formats=("8.3", "$10");
quit;

GROUPBY=(variable-list)

specifies a list of variable names, or a single variable name, to use as GROUPBY variables in the order of the grouping hierarchy. If you do not specify any GROUPBY variable names, then the calculation is performed across the entire table—possibly subject to a WHERE clause.

GROUPBYLIMIT=n

specifies the maximum number of levels in a GROUPBY set. When the software determines that there are at least n levels in the GROUPBY set, it abandons the action, returns a message, and does not produce a result set. You can specify the GROUPBYLIMIT= option if you want to avoid creating excessively large result sets in GROUPBY operations.

GROUPFILTER=(filter-options)

specifies a section of the group-by hierarchy to be included in the computation. With this option, you can request that the server performs the analysis for only a subset of all possible groupings. The subset is determined by applying the group filter to a temporary table that you generate with the GROUPBY statement.

You can specify the following suboptions in the GROUPFILTER option:

DESCENDING

specifies the top or the bottom section of the groupings to be collected. If the DESCENDING option is specified, the top LIMIT=n (where n > 0) groupings are collected. Otherwise, the bottom LIMIT=n groupings are collected.

Alias DESC

LIMIT=n

specifies the maximum number of distinct groupings to be collected, where integer n >= 0. If n is zero, then all distinct groupings (up to 2^31-1) that satisfy the boundary constraints, such as LOWERSCORE=f, are collected.

CAUTION:
High Cardinality Data Sets
Setting n to zero with high-cardinality data sets can significantly delay the response of the server.

SCOREGT=f

specifies the exclusive lower bound for the numeric scores of the distinct groupings to collect.

Alias SGT=

SCORELT=f

specifies the exclusive upper bound for the numeric scores of the distinct groupings to collect.

Alias SLT=

VALUEGT=("format-name1" <, "format-name2" ...>)

specifies the exclusive lower bound of the group-by variable’s formatted values for the distinct groupings to collect.

Alias VGT=

VALUELT=("format-name1" <, "format-name2" ...>)

specifies the exclusive upper bound of the group-by variable’s formatted values for the distinct groupings to collect.

Alias VLT=

TABLE=table-with-groupby-results

specifies the in-memory table from which to load the group-by hierarchy. If the TABLE= option is not specified, then all other GROUPFILTER= options are ignored.

The following program request all the groupings of State, City, and then Trade_In_Model in the Cars_Program_All table. The groupings are ordered by the maximum value of New_Vehicle_Msrp for each grouping:
proc imstat;
    table example.CARS_PROGRAM_ALL;
    groupby state city trade_in_model / TEMPTABLE 
                 WEIGHT=new_vehicle_MSRP 
                 AGG   =(MAX) 
                 ORDER =WEIGHT;  
run;
The TEMPTABLE option in the GROUPBY statement directs the server to save all the groupings in a temporary in-memory table. The following DISTINCT statement requests the count of the distinct unformatted values of Sales_Type for each of the selected groupings of State, City, and Trade_In_Model.
    table example.CARS_PROGRAM_ALL;
    distinct sales_type / GROUPFILTER=(
                 table  =mylasr.&_TEMPLAST_
                 scoregt=40000
                 valuelt=("FL","Ft Myers","")
                 limit  =20
                 descending);
run;
This example only considers groupings that have maximum values of the New_Vehicle_Msrp above 40,000 and with formatted values that are less than State="FL" and City="Ft Myers." The empty quotation marks result in no restriction on Trade_In_Model values. These groupings are ordered according to the maximum values of New_Vehicle_Msrp. Because of the DESCENDING option, this example collects the 20 top groupings within the specified group-by range for the DISTINCT analysis.
Interaction If you specify the GROUPFILTER= option, then the GROUPBY= and FORMATS= options have no effect.

LIMIT=n

limits the size of the result set returned to the SAS client. For example, the following SUMMARY statement returns the size (in number of records) of the largest partition for Table1.

Because of the PARTITION option, the rows are processed by partition and the summary request returns one row per partition. The ORDERBY= specification requests that the results are ordered by the variable Amount, and that the result is sorted in descending order with respect to the number of observations (AGGREGATE=N). Once the results are arranged this way, the first observation in the set is returned (LIMIT=1).
Example
proc imstat data=mylasr.Table1;
    summary Amount / partition orderby=(Amount) desc
                     aggregate=(N) limit=1;
run;

MERGEBINS=b

specifies the number of bins to create when a numeric GROUPBY variable exceeds the MERGELIMIT=n specification. If you specify a MERGELIMIT, but do not specify a value for the MERGEBINS= option, the server automatically calculates the number of bins.

MERGELIMIT=n

specifies that when the number of unique values in a numeric GROUPBY variable exceeds n, the variable is automatically binned and the GROUPBY structure is determined based on the binned values of the variable, rather than the unique formatted values.

For example, if you specify MERGELIMIT=500, any numeric GROUPBY variable with more than 500 unique formatted values is binned. Instead of returning results for more than 500 groups, the results are returned for the bins. You can specify the number of bins with the MERGEBINS= option.

DESCENDING

specifies that the levels of the GROUPBY variables are to be arranged in descending order.

Alias DESC

NOPREPARSE

prevents the procedure from pre-parsing and pre-generating code for temporary expressions, scoring programs, and other user-written SAS statements.

When this option is specified, the user-written statements are sent to the server "as-is" and then the server attempts to generate code from it. If the server detects problems with the code, the error messages might not to be as detailed as the messages that are generated by SAS client. If you are debugging your user-written program, then you might want to pre-parse and pre-generate code in the procedure. However, if your SAS statements compile and run as you want them to, then you can specify this option to avoid the work of parsing and generating code on the SAS client.
When you specify this option in the PROC IMSTAT statement, the option applies to all statements that can generate code. You can also exclude specific statements from pre-parsing by using the NOPREPARSE option in statements that allow temporary columns or the SCORE statement.
Alias NOPREP

NOTEMPPART

specifies that the temporary table generated by the TEMPTABLE option is not partitioned by the GROUPBY= variables. When you request a temporary table with the SUMMARY statement, by default, the server partitions the table and the size of a partition is equal to the number of analysis variables in the variable-list of the SUMMARY statement. When the number of groups is large, this can result in many small partitions, and requires extra memory resources to store the partition information for the temporary table. By specifying this option, the temporary table is organized similarly to the default table, but is not a partitioned table.

Alias NOTP

ORDERBY=(variable-list)

specifies the variables to use for ordering the result set. If a variable is not one of the numeric variables in the variable-list for the SUMMARY statement, it is assumed to be one of the GROUPBY variables.

ORDERDESC

specifies the sort order for the result set. The default is ascending order. Specify the ORDERDESC option to sort in descending order. Note that the ORDERDESC option is different from setting the DESCENDING option. The DESCENDING option affects the order of the values for the GROUPBY variables.

PARTITION <=partition-key>

When you specify this option and the table is partitioned, the results are calculated separately for each value of the partition key. In other words, the partition variables function as automatic GROUPBY variables. This mode of executing calculations by partition is more efficient than using the GROUPBY= option. With a partitioned table, the server takes advantage of knowing that observations for a partition cannot be located on more than one worker node.

If you do not specify a partition-key, the analysis is performed for all partitions. If you do specify a partition-key, the analysis is carried out for the specified key value only. You can use the PARTITIONINFO statement to retrieve the valid partition key values for a table.
You can specify a partition-key in two ways. You can supply a single quoted string that is passed to the server, or you can specify the elements of a composite key separated by commas. For example, if you partition a table by variables GENDER and AGE, with formats $1 and BEST12, respectively, then the composite partition key has a length of 13. You can specify the partition for the 11-year-old females as follows:
statement / partition="F          11"; /* passed directly to the server */
statement / partition="F","11";        /* composed by the procedure */
If you choose the second format, the procedure composes a key based on formatting information from the server.
Alias PART=

RAWORDER

specifies that the ordering of the GROUPBY variables is based on the raw values of the variables instead of the formatted values.

SAVE=table-name

saves the result table so that you can use it in other IMSTAT procedure statements like STORE, REPLAY, and FREE. The value for table-name must be unique within the scope of the procedure execution. The name of a table that has been freed with the FREE statement can be used again in subsequent SAVE= options.

SETSIZE

requests that the server estimate the size of the result set. The procedure does not create a result table if the SETSIZE option is specified. Instead, the procedure reports the number of rows that are returned by the request and the expected memory consumption for the result set (in KB). If you specify the SETSIZE option, the SAS log includes the number of observations and the estimated result set size. See the following log sample:

NOTE: The LASR Analytic Server action request for the STATEMENT
      statement would return 17 rows and approximately
      3.641 kBytes of data.
The typical use of the SETSIZE option is to get an estimate of the size of the result set in situations where you are unsure whether the SAS session can handle a large result set. Be aware that in order to determine the size of the result set, the server has to perform the work as if you were receiving the actual result set. Requesting the estimated size of the result set does consume resources on the server. The estimated number of KB is very close to the actual memory consumption of the result set. It might not be immediately obvious how this size relates to the displayed table, since many tables contain hidden columns. In addition, some elements of the result set might not be converted to tabular output by the procedure.

TEMPEXPRESS="SAS-expressions"

TEMPEXPRESS=file-reference

specifies either a quoted string that contains the SAS expression that defines the temporary variables or a file reference to an external file with the SAS statements.

Alias TE=

TEMPNAMES=variable-name

TEMPNAMES=(variable-list)

specifies the list of temporary variables for the request. Each temporary variable must be defined through SAS statements that you supply with the TEMPEXPRESS= option.

Alias TN=

TEMPTABLE

generates an in-memory temporary table from the result set. The IMSTAT procedure displays the name of the table and stores it in the &_TEMPLAST_ macro variable, provided that the statement executed successfully.

When the IMSTAT procedure exits, all temporary tables created during the IMSTAT session are removed. Temporary tables are not displayed on a TABLEINFO request, unless the temporary table is the active table for the request.

TWELVEBIN

specifies to augment the summary results with a 12-bin histogram. This option has no effect when the summaries are computed in GROUPBY or partitioned mode.