xsv is a command line program for indexing, slicing, analyzing, splitting and joining CSV files. Commands should be simple, fast and composable:
- Simple tasks should be easy.
- Performance trade offs should be exposed in the CLI interface.
- Composition should not come at the expense of performance.
This README contains information on how to
install xsv, in addition to
a quick tour of several commands.
Dual-licensed under MIT or the UNLICENSE.
Available commands
- cat - Concatenate CSV files by row or by column.
- count - Count the rows in a CSV file. (Instantaneous with an index.)
- fixlengths - Force a CSV file to have same-length records by either padding or truncating them.
- flatten - A flattened view of CSV records. Useful for viewing one record
at a time. e.g.,
xsv slice -i 5 data.csv | xsv flatten. - fmt - Reformat CSV data with different delimiters, record terminators or quoting rules. (Supports ASCII delimited data.)
- frequency - Build frequency tables of each column in CSV data. (Uses parallelism to go faster if an index is present.)
- headers - Show the headers of CSV data. Or show the intersection of all headers between many CSV files.
- index - Create an index for a CSV file. This is very quick and provides constant time indexing into the CSV file.
- input - Read CSV data with exotic quoting/escaping rules.
- join - Inner, outer and cross joins. Uses a simple hash index to make it fast.
- sample - Randomly draw rows from CSV data using reservoir sampling (i.e., use memory proportional to the size of the sample).
- search - Run a regex over CSV data. Applies the regex to each field individually and shows only matching rows.
- select - Select or re-order columns from CSV data.
- slice - Slice rows from any part of a CSV file. When an index is present, this only has to parse the rows in the slice (instead of all rows leading up to the start of the slice).
- sort - Sort CSV data.
- split - Split one CSV file into many CSV files of N chunks.
- stats - Show basic types and statistics of each column in the CSV file. (i.e., mean, standard deviation, median, range, etc.)
- table - Show aligned output of any CSV data using elastic tabstops.
A whirlwind tour
Let's say you're playing with some of the data from the Data Science Toolkit, which contains several CSV files. Maybe you're interested in the population counts of each city in the world. So grab the data and start examining it:
$ curl -LO http://burntsushi.net/stuff/worldcitiespop.csv
$ xsv headers worldcitiespop.csv
1 Country
2 City
3 AccentCity
4 Region
5 Population
6 Latitude
7 LongitudeThe next thing you might want to do is get an overview of the kind of data that
appears in each column. The stats command will do this for you:
$ xsv stats worldcitiespop.csv --everything | xsv table
field type min max min_length max_length mean stddev median mode cardinality
Country Unicode ad zw 2 2 cn 234
City Unicode bab el ahmar Þykkvibaer 1 91 san jose 2351892
AccentCity Unicode Bâb el Ahmar ïn Bou Chella 1 91 San Antonio 2375760
Region Unicode 00 Z9 0 2 13 04 397
Population Integer 7 31480498 0 8 47719.570634 302885.559204 10779 28754
Latitude Float -54.933333 82.483333 1 12 27.188166 21.952614 32.497222 51.15 1038349
Longitude Float -179.983333 180 1 14 37.08886 63.22301 35.28 23.8 1167162The xsv table command takes any CSV data and formats it into aligned columns
using elastic tabstops. You'll
notice that it even gets alignment right with respect to Unicode characters.
So, this command takes about 12 seconds to run on my machine, but we can speed it up by creating an index and re-running the command:
$ xsv index worldcitiespop.csv
$ xsv stats worldcitiespop.csv --everything | xsv table
...Which cuts it down to about 8 seconds on my machine. (And creating the index takes less than 2 seconds.)
Notably, the same type of "statistics" command in another CSV command line toolkit takes about 2 minutes to produce similar statistics on the same data set.
Creating an index gives us more than just faster statistics gathering. It also makes slice operations extremely fast because only the sliced portion has to be parsed. For example, let's say you wanted to grab the last 10 records:
$ xsv count worldcitiespop.csv
3173958
$ xsv slice worldcitiespop.csv -s 3173948 | xsv table
Country City AccentCity Region Population Latitude Longitude
zw zibalonkwe Zibalonkwe 06 -19.8333333 27.4666667
zw zibunkululu Zibunkululu 06 -19.6666667 27.6166667
zw ziga Ziga 06 -19.2166667 27.4833333
zw zikamanas village Zikamanas Village 00 -18.2166667 27.95
zw zimbabwe Zimbabwe 07 -20.2666667 30.9166667
zw zimre park Zimre Park 04 -17.8661111 31.2136111
zw ziyakamanas Ziyakamanas 00 -18.2166667 27.95
zw zizalisari Zizalisari 04 -17.7588889 31.0105556
zw zuzumba Zuzumba 06 -20.0333333 27.9333333
zw zvishavane Zvishavane 07 79876 -20.3333333 30.0333333These commands are instantaneous because they run in time and memory proportional to the size of the slice (which means they will scale to arbitrarily large CSV data).
Switching gears a little bit, you might not always want to see every column in the CSV data. In this case, maybe we only care about the country, city and population. So let's take a look at 10 random rows:
$ xsv select Country,AccentCity,Population worldcitiespop.csv \
| xsv sample 10 \
| xsv table
Country AccentCity Population
cn Guankoushang
za Klipdrift
ma Ouled Hammou
fr Les Gravues
la Ban Phadèng
de Lüdenscheid 80045
qa Umm ash Shubrum
bd Panditgoan
us Appleton
ua LukashenkivskeWhoops! It seems some cities don't have population counts. How pervasive is that?
$ xsv frequency worldcitiespop.csv --limit 5
field,value,count
Country,cn,238985
Country,ru,215938
Country,id,176546
Country,us,141989
Country,ir,123872
City,san jose,328
City,san antonio,320
City,santa rosa,296
City,santa cruz,282
City,san juan,255
AccentCity,San Antonio,317
AccentCity,Santa Rosa,296
AccentCity,Santa Cruz,281
AccentCity,San Juan,254
AccentCity,San Miguel,254
Region,04,159916
Region,02,142158
Region,07,126867
Region,03,122161
Region,05,118441
Population,(NULL),3125978
Population,2310,12
Population,3097,11
Population,983,11
Population,2684,11
Latitude,51.15,777
Latitude,51.083333,772
Latitude,50.933333,769
Latitude,51.116667,769
Latitude,51.133333,767
Longitude,23.8,484
Longitude,23.2,477
Longitude,23.05,476
Longitude,25.3,474
Longitude,23.1,459(The xsv frequency command builds a frequency table for each column in the
CSV data. This one only took 5 seconds.)
So it seems that most cities do not have a population count associated with them at all. No matter—we can adjust our previous command so that it only shows rows with a population count:
$ xsv search -s Population '[0-9]' worldcitiespop.csv \
| xsv select Country,AccentCity,Population \
| xsv sample 10 \
| xsv table
Country AccentCity Population
es Barañáin 22264
es Puerto Real 36946
at Moosburg 4602
hu Hejobaba 1949
ru Polyarnyye Zori 15092
gr Kandíla 1245
is Ólafsvík 992
hu Decs 4210
bg Sliven 94252
gb Leatherhead 43544Erk. Which country is at? No clue, but the Data Science Toolkit has a CSV
file called countrynames.csv. Let's grab it and do a join so we can see which
countries these are:
curl -LO https://gist.githubusercontent.com/anonymous/063cb470e56e64e98cf1/raw/98e2589b801f6ca3ff900b01a87fbb7452eb35c7/countrynames.csv
$ xsv headers countrynames.csv
1 Abbrev
2 Country
$ xsv join --no-case Country sample.csv Abbrev countrynames.csv | xsv table
Country AccentCity Population Abbrev Country
es Barañáin 22264 ES Spain
es Puerto Real 36946 ES Spain
at Moosburg 4602 AT Austria
hu Hejobaba 1949 HU Hungary
ru Polyarnyye Zori 15092 RU Russian Federation | Russia
gr Kandíla 1245 GR Greece
is Ólafsvík 992 IS Iceland
hu Decs 4210 HU Hungary
bg Sliven 94252 BG Bulgaria
gb Leatherhead 43544 GB Great Britain | UK | England | Scotland | Wales | Northern Ireland | United KingdomWhoops, now we have two columns called Country and an Abbrev column that we
no longer need. This is easy to fix by re-ordering columns with the xsv select command:
$ xsv join --no-case Country sample.csv Abbrev countrynames.csv \
| xsv select 'Country[1],AccentCity,Population' \
| xsv table
Country AccentCity Population
Spain Barañáin 22264
Spain Puerto Real 36946
Austria Moosburg 4602
Hungary Hejobaba 1949
Russian Federation | Russia Polyarnyye Zori 15092
Greece Kandíla 1245
Iceland Ólafsvík 992
Hungary Decs 4210
Bulgaria Sliven 94252
Great Britain | UK | England | Scotland | Wales | Northern Ireland | United Kingdom Leatherhead 43544Perhaps we can do this with the original CSV data? Indeed we can—because
joins in xsv are fast.
$ xsv join --no-case Abbrev countrynames.csv Country worldcitiespop.csv \
| xsv select '!Abbrev,Country[1]' \
> worldcitiespop_countrynames.csv
$ xsv sample 10 worldcitiespop_countrynames.csv | xsv table
Country City AccentCity Region Population Latitude Longitude
Sri Lanka miriswatte Miriswatte 36 7.2333333 79.9
Romania livezile Livezile 26 1985 44.512222 22.863333
Indonesia tawainalu Tawainalu 22 -4.0225 121.9273
Russian Federation | Russia otar Otar 45 56.975278 48.305278
France le breuil-bois robert le Breuil-Bois Robert A8 48.945567 1.717026
France lissac Lissac B1 45.103094 1.464927
Albania lumalasi Lumalasi 46 40.6586111 20.7363889
China motzushih Motzushih 11 27.65 111.966667
Russian Federation | Russia svakino Svakino 69 55.60211 34.559785
Romania tirgu pancesti Tirgu Pancesti 38 46.216667 27.1The !Abbrev,Country[1] syntax means, "remove the Abbrev column and remove
the second occurrence of the Country column." Since we joined with
countrynames.csv first, the first Country name (fully expanded) is now
included in the CSV data.
This xsv join command takes about 7 seconds on my machine. The performance
comes from constructing a very simple hash index of one of the CSV data files
given. The join command does an inner join by default, but it also has left,
right and full outer join support too.
Installation
Binaries for Windows, Linux and Mac are available from Github.
If you're a Mac OS X Homebrew user, then you can install xsv from homebrew-core:
$ brew install xsv
Alternatively, you can compile from source by
installing Cargo
(Rust's package manager)
and installing xsv using Cargo:
cargo install xsvCompiling from this repository also works similarly:
git clone git://github.com/BurntSushi/xsv
cd xsv
cargo build --releaseCompilation will probably take a few minutes depending on your machine. The
binary will end up in ./target/release/xsv.
Benchmarks
I've compiled some very rough
benchmarks of
various xsv commands.
Motivation
Here are several valid criticisms of this project:
- You shouldn't be working with CSV data because CSV is a terrible format.
- If your data is gigabytes in size, then CSV is the wrong storage type.
- Various SQL databases provide all of the operations available in
xsvwith more sophisticated indexing support. And the performance is a zillion times better.
I'm sure there are more criticisms, but the impetus for this project was a 40GB CSV file that was handed to me. I was tasked with figuring out the shape of the data inside of it and coming up with a way to integrate it into our existing system. It was then that I realized that every single CSV tool I knew about was woefully inadequate. They were just too slow or didn't provide enough flexibility. (Another project I had comprised of a few dozen CSV files. They were smaller than 40GB, but they were each supposed to represent the same kind of data. But they all had different column and unintuitive column names. Useful CSV inspection tools were critical here—and they had to be reasonably fast.)
The key ingredients for helping me with my task were indexing, random sampling, searching, slicing and selecting columns. All of these things made dealing with 40GB of CSV data a bit more manageable (or dozens of CSV files).
Getting handed a large CSV file once was enough to launch me on this quest. From conversations I've had with others, CSV data files this large don't seem to be a rare event. Therefore, I believe there is room for a tool that has a hope of dealing with data that large.