36 lines
1.6 KiB
Factor
36 lines
1.6 KiB
Factor
USING: help.markup help.syntax sequences ;
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IN: columns
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HELP: column
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{ $class-description "A virtual sequence which presents a fixed column of a matrix represented as a sequence of rows. New instances can be created by calling " { $link <column> } "." } ;
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HELP: <column>
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{ $values { "seq" sequence } { "col" "a non-negative integer" } { "column" column } }
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{ $description "Outputs a new virtual sequence which presents a fixed column of a matrix represented as a sequence of rows." "The " { $snippet "i" } "th element of a column is the " { $snippet "n" } "th element of the " { $snippet "i" } "th element of " { $snippet "seq" } ". Every element of " { $snippet "seq" } " must be a sequence, and all sequences must have equal length." }
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{ $examples
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{ $example
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"USING: arrays prettyprint columns ;"
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"{ { 1 2 3 } { 4 5 6 } { 7 8 9 } } 0 <column> >array ."
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"{ 1 4 7 }"
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}
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}
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{ $notes
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"In the same sense that " { $link <reversed> } " is a virtual variant of " { $link reverse } ", " { $link <column> } " is a virtual variant of " { $snippet "swap [ nth ] curry map" } "."
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} ;
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HELP: <flipped>
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{ $values { "seq" sequence } { "seq'" sequence } }
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{ $description "Outputs a new virtual sequence which presents the transpose of " { $snippet "seq" } "." }
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{ $notes "This is the virtual sequence equivalent of " { $link flip } "." } ;
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ARTICLE: "columns" "Column sequences"
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"A " { $emphasis "column" } " presents a column of a matrix represented as a sequence of rows:"
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{ $subsections
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column
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<column>
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}
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"A utility word:"
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{ $subsections <flipped> } ;
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ABOUT: "columns"
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