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This post will show you how to do better. toString function fails (1) because it has to materialize the whole thing thing in memory, and (3) because it has to construct the entire output string before you can see any output at all. Note that most common pretty-printers fail these requirements. first 100 lines) to figure out what you need, and you shouldn't need to pay to pretty-print the entire structure.
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For large structures, you often only need to see part of it (e.g. Laziness: I should be able to print only the part of the structure that I want, and then stop. Linear execution time: pretty-printing should take time proportional to the thing you are trying to print, and shouldn't scale quadratically or exponentially when that thing gets bigger The last requirement that is often seen in pretty-printing is that of efficiency:Ĭonstant heap usage: I would want to be able to pretty print large data structures without needing to load it all into memory at the same time for manipulation. Here, we see more items laid out horizontally: the entire "person1" in the JSON example fits on one line, as does the entire model in the Python example, while "person2" is still too long to fit within the 80 character limit without wrapping. Model = Sequential(Dense(512, activation=relu), Dense(10, activation=softmax)) Let us consider two samples of hierarchical data, formatted to fit within a 50 character wide screen. While some data formats have interactive GUIs to let you explore them, in most cases that job falls to the pretty-printer to convert the data structure into a plain-text string that is sufficiently nicely formatted that someone can skim over it and find what they want without undue difficulty. Binary data, of course, needs to be converted to textual data for human readability. However, the same textual data can be formatted a variety of ways: perhaps it was written without strong style conventions, or minified to send over the wire. Many data formats are hierarchical: whether textual formats like JSON or YAML, binary formats like MessagePack or Protobuf, or even program source code in common languages like Java or Python. If you enjoyed the contents on this blog, you may also enjoy Haoyi's book Hands-on Scala Programming
#SCALA PRINT SOFTWARE#
This post presents an algorithm which achieves optimal usage of horizontal space, predictable layout, and good runtime characteristics: peak heap usage linear in the width of the output window, the ability to start and stop the pretty-printing to print any portion of it, with total runtime linear in the portion of the structure printed.Ībout the Author: Haoyi is a software engineer, and the author of many open-source Scala tools such as the Ammonite REPL and the Mill Build Tool.
#SCALA PRINT FULL#
While a computer doesn't care exactly how you format the same textual data, a human would want to view data that is nicely laid out and indented, yet compact enough to make full use of the width of the output window and avoid wasting horizontal screen space. Pretty-printing hierarchical data into a human-readable form is a common thing to do. Automatic Binary Serialization in uPickle 0.7 How to work with Files in Scala