X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=doc%2Fdata-selection.texi;h=a8cb12d95364d95c0525ec06974cac9c7981fdfc;hb=refs%2Fheads%2Flexer;hp=04269f32413733af6d626c3320b3142755264912;hpb=9a331fe64eb814ae5c1322e21717a04fb254bf65;p=pspp diff --git a/doc/data-selection.texi b/doc/data-selection.texi index 04269f3241..a8cb12d953 100644 --- a/doc/data-selection.texi +++ b/doc/data-selection.texi @@ -1,12 +1,12 @@ @node Data Selection @chapter Selecting data for analysis -This chapter documents PSPP commands that temporarily or permanently -select data records from the active file for analysis. +This chapter documents @pspp{} commands that temporarily or permanently +select data records from the active dataset for analysis. @menu * FILTER:: Exclude cases based on a variable. -* N OF CASES:: Limit the size of the active file. +* N OF CASES:: Limit the size of the active dataset. * SAMPLE:: Select a specified proportion of cases. * SELECT IF:: Permanently delete selected cases. * SPLIT FILE:: Do multiple analyses with one command. @@ -19,14 +19,14 @@ select data records from the active file for analysis. @vindex FILTER @display -FILTER BY var_name. +FILTER BY @var{var_name}. FILTER OFF. @end display @cmd{FILTER} allows a boolean-valued variable to be used to select cases from the data stream for processing. -To set up filtering, specify BY and a variable name. Keyword +To set up filtering, specify @subcmd{BY} and a variable name. Keyword BY is optional but recommended. Cases which have a zero or system- or user-missing value are excluded from analysis, but not deleted from the data stream. Cases with other values are analyzed. @@ -40,7 +40,7 @@ filter variable of the required form, then specify that variable on Filtering takes place immediately before cases pass to a procedure for analysis. Only one filter variable may be active at a time. Normally, case filtering continues until it is explicitly turned off with @code{FILTER -OFF}. However, if @cmd{FILTER} is placed after TEMPORARY, it filters only +OFF}. However, if @cmd{FILTER} is placed after @cmd{TEMPORARY}, it filters only the next procedure or procedure-like command. @node N OF CASES @@ -48,12 +48,12 @@ the next procedure or procedure-like command. @vindex N OF CASES @display -N [OF CASES] num_of_cases [ESTIMATED]. +N [OF CASES] @var{num_of_cases} [ESTIMATED]. @end display @cmd{N OF CASES} limits the number of cases processed by any procedures that follow it in the command stream. @code{N OF CASES -100}, for example, tells PSPP to disregard all cases after the first +100}, for example, tells @pspp{} to disregard all cases after the first 100. When @cmd{N OF CASES} is specified after @cmd{TEMPORARY}, it affects @@ -61,56 +61,56 @@ only the next procedure (@pxref{TEMPORARY}). Otherwise, cases beyond the limit specified are not processed by any later procedure. If the limit specified on @cmd{N OF CASES} is greater than the number -of cases in the active file, it has no effect. +of cases in the active dataset, it has no effect. When @cmd{N OF CASES} is used along with @cmd{SAMPLE} or @cmd{SELECT IF}, the case limit is applied to the cases obtained after sampling or case selection, regardless of how @cmd{N OF CASES} is placed relative to @cmd{SAMPLE} or @cmd{SELECT IF} in the command file. Thus, the commands @code{N OF CASES 100} and @code{SAMPLE .5} will both randomly -sample approximately half of the active file's cases, then select the +sample approximately half of the active dataset's cases, then select the first 100 of those sampled, regardless of their order in the command file. @cmd{N OF CASES} with the @code{ESTIMATED} keyword gives an estimated number of cases before @cmd{DATA LIST} or another command to read in data. @code{ESTIMATED} never limits the number of cases processed by -procedures. PSPP currently does not make use of case count estimates. +procedures. @pspp{} currently does not make use of case count estimates. @node SAMPLE @section SAMPLE @vindex SAMPLE @display -SAMPLE num1 [FROM num2]. +SAMPLE @var{num1} [FROM @var{num2}]. @end display @cmd{SAMPLE} randomly samples a proportion of the cases in the active file. Unless it follows @cmd{TEMPORARY}, it operates as a -transformation, permanently removing cases from the active file. +transformation, permanently removing cases from the active dataset. The proportion to sample can be expressed as a single number between 0 -and 1. If @code{k} is the number specified, and @code{N} is the number -of currently-selected cases in the active file, then after -@code{SAMPLE @var{k}.}, approximately @code{k*N} cases will be +and 1. If @var{k} is the number specified, and @var{N} is the number +of currently-selected cases in the active dataset, then after +@subcmd{SAMPLE @var{k}.}, approximately @var{k}*@var{N} cases will be selected. -The proportion to sample can also be specified in the style @code{SAMPLE +The proportion to sample can also be specified in the style @subcmd{SAMPLE @var{m} FROM @var{N}}. With this style, cases are selected as follows: @enumerate @item If @var{N} is equal to the number of currently-selected cases in the -active file, exactly @var{m} cases will be selected. +active dataset, exactly @var{m} cases will be selected. @item If @var{N} is greater than the number of currently-selected cases in the -active file, an equivalent proportion of cases will be selected. +active dataset, an equivalent proportion of cases will be selected. @item If @var{N} is less than the number of currently-selected cases in the active, exactly @var{m} cases will be selected @emph{from the first -@var{N} cases in the active file.} +@var{N} cases in the active dataset.} @end enumerate @cmd{SAMPLE} and @cmd{SELECT IF} are performed in @@ -131,12 +131,12 @@ random number seed is based on the system time. @vindex SELECT IF @display -SELECT IF expression. +SELECT IF @var{expression}. @end display -@cmd{SELECT IF} selects cases for analysis based on the value of a -boolean expression. Cases not selected are permanently eliminated -from the active file, unless @cmd{TEMPORARY} is in effect +@cmd{SELECT IF} selects cases for analysis based on the value of +@var{expression}. Cases not selected are permanently eliminated +from the active dataset, unless @cmd{TEMPORARY} is in effect (@pxref{TEMPORARY}). Specify a boolean expression (@pxref{Expressions}). If the value of the @@ -157,7 +157,7 @@ When @cmd{SELECT IF} is specified following @cmd{TEMPORARY} @vindex SPLIT FILE @display -SPLIT FILE [@{LAYERED, SEPARATE@}] BY var_list. +SPLIT FILE [@{LAYERED, SEPARATE@}] BY @var{var_list}. SPLIT FILE OFF. @end display @@ -172,15 +172,15 @@ An independent analysis is carried out for each group of cases, and the variable values for the group are printed along with the analysis. When a list of variable names is specified, one of the keywords -LAYERED or SEPARATE may also be specified. If provided, either +@subcmd{LAYERED} or @subcmd{SEPARATE} may also be specified. If provided, either keyword are ignored. Groups are formed only by @emph{adjacent} cases. To create a split using a variable where like values are not adjacent in the working file, you should first sort the data by that variable (@pxref{SORT CASES}). -Specify OFF to disable @cmd{SPLIT FILE} and resume analysis of the -entire active file as a single group of data. +Specify @subcmd{OFF} to disable @cmd{SPLIT FILE} and resume analysis of the +entire active dataset as a single group of data. When @cmd{SPLIT FILE} is specified after @cmd{TEMPORARY}, it affects only the next procedure (@pxref{TEMPORARY}). @@ -196,7 +196,7 @@ TEMPORARY. @cmd{TEMPORARY} is used to make the effects of transformations following its execution temporary. These transformations will affect only the execution of the next procedure or procedure-like -command. Their effects will not be saved to the active file. +command. Their effects will not be saved to the active dataset. The only specification on @cmd{TEMPORARY} is the command name. @@ -218,9 +218,12 @@ BEGIN DATA. 20 24 END DATA. + COMPUTE X=X/2. + TEMPORARY. COMPUTE X=X+3. + DESCRIPTIVES X. DESCRIPTIVES X. @end example @@ -234,21 +237,21 @@ The data read by the first @cmd{DESCRIPTIVES} are 4, 5, 8, @vindex WEIGHT @display -WEIGHT BY var_name. +WEIGHT BY @var{var_name}. WEIGHT OFF. @end display @cmd{WEIGHT} assigns cases varying weights, -changing the frequency distribution of the active file. Execution of +changing the frequency distribution of the active dataset. Execution of @cmd{WEIGHT} is delayed until data have been read. If a variable name is specified, @cmd{WEIGHT} causes the values of that variable to be used as weighting factors for subsequent statistical -procedures. Use of keyword BY is optional but recommended. Weighting +procedures. Use of keyword @subcmd{BY} is optional but recommended. Weighting variables must be numeric. Scratch variables may not be used for weighting (@pxref{Scratch Variables}). -When OFF is specified, subsequent statistical procedures will weight all +When @subcmd{OFF} is specified, subsequent statistical procedures will weight all cases equally. A positive integer weighting factor @var{w} on a case will yield the @@ -262,5 +265,5 @@ values are not treated specially. When @cmd{WEIGHT} is specified after @cmd{TEMPORARY}, it affects only the next procedure (@pxref{TEMPORARY}). -@cmd{WEIGHT} does not cause cases in the active file to be replicated in -memory. +@cmd{WEIGHT} does not cause cases in the active dataset to be +replicated in memory.