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151 lines
7.7 KiB
Markdown
151 lines
7.7 KiB
Markdown
# What is Miller?
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**Miller is like awk, sed, cut, join, and sort for name-indexed data such as CSV, TSV, and tabular JSON.**
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# Build status
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[](https://travis-ci.org/johnkerl/miller)
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[](https://ci.appveyor.com/project/johnkerl/miller)
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[](https://github.com/johnkerl/miller/blob/master/LICENSE.txt)
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[](http://johnkerl.org/miller/doc)
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# Distributions
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There's a good chance you can get Miller pre-built for your system:
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[](https://launchpad.net/ubuntu/+source/miller)
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[](https://launchpad.net/ubuntu/xenial/+package/miller)
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[](https://apps.fedoraproject.org/packages/miller)
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[](https://packages.debian.org/stable/miller)
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[](https://packages.gentoo.org/packages/sys-apps/miller)
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[](http://www.pro-linux.de/cgi-bin/DBApp/check.cgi?ShowApp..20427.100)
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[](https://aur.archlinux.org/packages/miller-git)
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[](http://pkgsrc.se/textproc/miller)
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[](https://www.freshports.org/textproc/miller/)
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[](https://github.com/Homebrew/homebrew-core/search?utf8=%E2%9C%93&q=miller)
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[](https://www.macports.org/ports.php?by=name&substr=miller)
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[](https://chocolatey.org/packages/miller)
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|OS|Installation command|
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|---|---|
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|Linux|`yum install miller`<br/> `apt-get install miller`|
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|Mac|`brew install miller`<br/>`port install miller`|
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|Windows|`choco install miller`|
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See also [building from source](http://johnkerl.org/miller/doc/build.html#Building_from_source).
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# What can Miller do for me?
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With Miller, you get to use named fields without needing to count positional
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indices, using familiar formats such as CSV, TSV, JSON, and positionally-indexed.
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For example, suppose you have a CSV data file like this:
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```
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county,tiv_2011,tiv_2012,line,construction
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SEMINOLE,22890.55,20848.71,Residential,Wood
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MIAMI DADE,1158674.85,1076001.08,Residential,Masonry
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PALM BEACH,1174081.5,1856589.17,Residential,Masonry
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MIAMI DADE,2850980.31,2650932.72,Commercial,Reinforced Masonry
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HIGHLANDS,23006.41,19757.91,Residential,Wood
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HIGHLANDS,49155.16,47362.96,Residential,Wood
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DUVAL,1731888.18,2785551.63,Residential,Masonry
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ST. JOHNS,29589.12,35207.53,Residential,Wood
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```
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Then, on the fly, you can add new fields which are functions of existing fields, drop fields, sort, aggregate statistically, pretty-print, and more:
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```
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$ mlr --icsv --opprint --barred \
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put '$tiv_delta = $tiv_2012 - $tiv_2011; unset $tiv_2011, $tiv_2012' \
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then sort -nr tiv_delta flins.csv
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+------------+-------------+----------------+
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| county | line | tiv_delta |
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+------------+-------------+----------------+
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| Duval | Residential | 1053663.450000 |
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| Palm Beach | Residential | 682507.670000 |
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| St. Johns | Residential | 5618.410000 |
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| Highlands | Residential | -1792.200000 |
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| Seminole | Residential | -2041.840000 |
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| Highlands | Residential | -3248.500000 |
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| Miami Dade | Residential | -82673.770000 |
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| Miami Dade | Commercial | -200047.590000 |
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+------------+-------------+----------------+
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```
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This is something the Unix toolkit always could have done, and arguably always
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should have done.
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* Miller operates on **key-value-pair data** while the familiar
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Unix tools operate on integer-indexed fields: if the natural data structure for
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the latter is the array, then Miller's natural data structure is the
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insertion-ordered hash map.
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* Miller handles a **variety of data formats**,
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including but not limited to the familiar **CSV**, **TSV**, and **JSON**.
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(Miller can handle **positionally-indexed data** too!)
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For a few more examples please see [Miller in 10 minutes](http://johnkerl.org/miller/doc/10-min.html).
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# Features
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* Miller is **multi-purpose**: it's useful for **data cleaning**,
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**data reduction**, **statistical reporting**, **devops**, **system
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administration**, **log-file processing**, **format conversion**, and
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**database-query post-processing**.
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* You can use Miller to snarf and munge **log-file data**, including selecting
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out relevant substreams, then produce CSV format and load that into
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all-in-memory/data-frame utilities for further statistical and/or graphical
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processing.
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* Miller complements **data-analysis tools** such as **R**, **pandas**, etc.:
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you can use Miller to **clean** and **prepare** your data. While you can do
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**basic statistics** entirely in Miller, its streaming-data feature and
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single-pass algorithms enable you to **reduce very large data sets**.
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* Miller complements SQL **databases**: you can slice, dice, and reformat data
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on the client side on its way into or out of a database. You can also reap some
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of the benefits of databases for quick, setup-free one-off tasks when you just
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need to query some data in disk files in a hurry.
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* Miller also goes beyond the classic Unix tools by stepping fully into our
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modern, **no-SQL** world: its essential record-heterogeneity property allows
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Miller to operate on data where records with different schema (field names) are
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interleaved.
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* Miller is **streaming**: most operations need only a single record in
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memory at a time, rather than ingesting all input before producing any output.
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For those operations which require deeper retention (`sort`, `tac`, `stats1`),
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Miller retains only as much data as needed. This means that whenever
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functionally possible, you can operate on files which are larger than your
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system’s available RAM, and you can use Miller in **tail -f** contexts.
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* Miller is **pipe-friendly** and interoperates with the Unix toolkit
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* Miller's I/O formats include **tabular pretty-printing**, **positionally
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indexed** (Unix-toolkit style), CSV, JSON, and others
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* Miller does **conversion** between formats
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* Miller's **processing is format-aware**: e.g. CSV `sort` and `tac` keep header
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lines first
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* Miller has high-throughput **performance** on par with the Unix toolkit
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* Not unlike `jq` (http://stedolan.github.io/jq/) for JSON, Miller is written
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in portable, modern C, with **zero runtime dependencies**. You can download or
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compile a single binary, `scp` it to a faraway machine, and expect it to work.
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# Documentation links
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* [**Full documentation for latest release**](http://johnkerl.org/miller/doc)
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* [Head docs](http://johnkerl.org/miller-releases/miller-head/doc/index.html) match
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[head code](https://github.com/johnkerl/miller); [release-specific docs](http://johnkerl.org/miller/doc/release-docs.html)
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match [release-specific code](https://github.com/johnkerl/miller/tags).
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* [Miller's license is two-clause BSD](https://github.com/johnkerl/miller/blob/master/LICENSE.txt).
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* [Build information including dependencies](http://johnkerl.org/miller/doc/build.html)
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* [Notes about issue-labeling in the Github repo](https://github.com/johnkerl/miller/wiki/Issue-labeling)
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* [Active issues](https://github.com/johnkerl/miller/issues?q=is%3Aissue+is%3Aopen+sort%3Aupdated-desc)
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