The Read command reads a fixed amount of data from a file that has been opened with FileTools[Compressed][Open].

$\mathrm{file}≔\mathrm{FileTools}\left[\mathrm{TemporaryFilename}\right]\left(\mathrm{FileTools}\left[\mathrm{JoinPath}\right]\left(\left[\mathrm{FileTools}\left[\mathrm{TemporaryDirectory}\right]\left(\right)\,''GZtest-''\right]\right)\right)$

$\mathrm{file}≔''/tmp/mpldoc6/GZtest-yYoYxV9R''$

$\mathrm{data}≔\mathrm{LinearAlgebra}\left[\mathrm{RandomVector}\right]\left(100\,\mathrm{datatype}=\mathrm{float}\left[8\right]\right)$

$\mathrm{data}≔\begin{array}{c}\left[\begin{array}{c}\mathrm{-55.}\\ 17.\\ \mathrm{-35.}\\ 36.\\ 71.\\ 75.\\ 47.\\ \mathrm{-15.}\\ \mathrm{-48.}\\ \mathrm{-38.}\\ ⋮\end{array}\right]\\ \hfill \text{100 element Vector[column]}\end{array}$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{WriteFile}\right]\left(\mathrm{file}\,\mathrm{data}\right)$

$800$

$\mathrm{fd}≔\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Open}\right]\left(\mathrm{file}\right)$

$\mathrm{fd}≔825071248$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Read}\right]\left(\mathrm{fd}\,\mathrm{float}\left[8\right]\,1\right)\left[1\right]$

$\mathrm{-55.}$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Read}\right]\left(\mathrm{file}\,\mathrm{float}\left[8\right]\,99\right)$

$\left[\begin{array}{ccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc}17.& \mathrm{-35.}& 36.& 71.& 75.& 47.& \mathrm{-15.}& \mathrm{-48.}& \mathrm{-38.}& \mathrm{-80.}& 48.& \mathrm{-13.}& 76.& 5.& \mathrm{-2.}& 5.& 92.& 74.& \mathrm{-24.}& \mathrm{-28.}& \mathrm{-63.}& \mathrm{-19.}& \mathrm{-74.}& 83.& 95.& 25.& \mathrm{-69.}& 27.& 16.& 83.& 81.& 38.& \mathrm{-63.}& 1.& \mathrm{-25.}& \mathrm{-95.}& \mathrm{-77.}& \mathrm{-49.}& \mathrm{-24.}& \mathrm{-66.}& \mathrm{-28.}& \mathrm{-47.}& 87.& \mathrm{-99.}& 77.& 8.& \mathrm{-33.}& 49.& \mathrm{-63.}& \mathrm{-25.}& \mathrm{-1.}& \mathrm{-31.}& \mathrm{-88.}& 64.& \mathrm{-62.}& 4.& 69.& \mathrm{-63.}& \mathrm{-87.}& \mathrm{-34.}& 64.& 81.& 25.& 65.& 98.& 51.& 11.& 51.& 95.& \mathrm{-11.}& 34.& 46.& 9.& 50.& \mathrm{-43.}& \mathrm{-67.}& 19.& 29.& \mathrm{-12.}& 96.& 93.& \mathrm{-80.}& \mathrm{-92.}& \mathrm{-29.}& 96.& 89.& \mathrm{-55.}& \mathrm{-67.}& 77.& \mathrm{-70.}& 13.& \mathrm{-58.}& \mathrm{-94.}& \mathrm{-7.}& 12.& \mathrm{-53.}& 21.& \mathrm{-25.}& 40.\end{array}\right]$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Close}\right]\left(\mathrm{fd}\right)$

$0$

$\mathrm{FileTools}\left[\mathrm{Remove}\right]\left(\mathrm{file}\right)$

$\mathrm{zipfile}≔\mathrm{FileTools}\left[\mathrm{TemporaryFilename}\right]\left(\mathrm{cat}\left(\mathrm{FileTools}\left[\mathrm{TemporaryDirectory}\right]\left(\right)\,\mathrm{kernelopts}\left(\mathrm{dirsep}\right)\,''GZtest-''\right)\,''.zip''\right)$

$\mathrm{zipfile}≔''/tmp/mpldoc6/GZtest-AyUYslLY.zip''$

FileTools[Compressed][WriteFile]("sample" in zipfile, "A sample message");

$16$

fd := FileTools[Compressed][Open]("sample" in zipfile,'mode'=READ);

$\mathrm{fd}≔1$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Read}\right]\left(\mathrm{fd}\,\mathrm{string}\,8\right)$

$''A\; sample''$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Read}\right]\left(\mathrm{fd}\,\mathrm{string}\,8\right)$

$''message''$

$\mathrm{FileTools}\left[\mathrm{Compressed}\right]\left[\mathrm{Close}\right]\left(\mathrm{fd}\right)$

$0$

$\mathrm{FileTools}\left[\mathrm{Remove}\right]\left(\mathrm{zipfile}\right)$

The FileTools[Compressed][Read] command was introduced in Maple 16.

For more information on Maple 16 changes, see Updates in Maple 16.