pricehist/README.md
2021-08-17 12:58:49 +02:00

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# pricehist
A command-line tool for fetching and formatting historical price data, with
support for multiple data sources and output formats.
[![Pipeline status](https://gitlab.com/chrisberkhout/pricehist/badges/master/pipeline.svg)](https://gitlab.com/chrisberkhout/pricehist/-/commits/master)
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[![PyPI version](https://badge.fury.io/py/pricehist.svg)](https://badge.fury.io/py/pricehist)
[![Downloads](https://pepy.tech/badge/pricehist)](https://pepy.tech/project/pricehist)
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[![Code style](https://img.shields.io/badge/code%20style-black-000000.svg)](https://github.com/psf/black)
## Installation
Install via pip or
[pipx](https://pypa.github.io/pipx/):
```
pipx install pricehist
```
## Sources
- **`alphavantage`**: [Alpha Vantage](https://www.alphavantage.co/)
- **`coindesk`**: [CoinDesk Bitcoin Price Index](https://www.coindesk.com/coindesk-api)
- **`coinmarketcap`**: [CoinMarketCap](https://coinmarketcap.com/)
- **`ecb`**: [European Central Bank Euro foreign exchange reference rates](https://www.ecb.europa.eu/stats/exchange/eurofxref/html/index.en.html)
- **`yahoo`**: [Yahoo! Finance](https://finance.yahoo.com/)
## Output formats
- **`beancount`**: [Beancount](http://furius.ca/beancount/)
- **`csv`**: [Comma-separated values](https://en.wikipedia.org/wiki/Comma-separated_values)
- **`gnucash-sql`**: [GnuCash](https://www.gnucash.org/) SQL
- **`ledger`**: [Ledger](https://www.ledger-cli.org/) and [hledger](https://hledger.org/)
## Usage
### Fetch prices
Fetch prices by choosing a source, a pair and, optionally, a time interval:
```
pricehist fetch ecb EUR/AUD -s 2021-01-04 -e 2021-01-08
```
```
date,base,quote,amount,source,type
2021-01-04,EUR,AUD,1.5928,ecb,reference
2021-01-05,EUR,AUD,1.5927,ecb,reference
2021-01-06,EUR,AUD,1.5824,ecb,reference
2021-01-07,EUR,AUD,1.5836,ecb,reference
2021-01-08,EUR,AUD,1.5758,ecb,reference
```
The default output format is CSV, which is suitable for use in spreadsheets and
with other tools. For example, on the command line using
[gnuplot](http://www.gnuplot.info/) we can chart Bitcoin prices:
```
pricehist fetch coindesk BTC/USD -s 2021-01-01 | \
cut -d, -f1,4 | \
sed 1d | \
gnuplot -p -e '
set datafile separator ",";
set xdata time;
set timefmt "%Y-%m-%d";
set format x "%b\n%Y";
plot "/dev/stdin" using 1:2 with lines title "BTC/USD"
'
```
![BTC/USD prices](example-gnuplot.png)
### Show usage information
Add `-h` to any command to see usage information:
```
pricehist fetch -h
```
```
usage: pricehist fetch SOURCE PAIR [-h] [-vvv] [-t TYPE] [-s DATE | -sx DATE] [-e DATE | -ex DATE]
[-o beancount|csv|gnucash-sql|ledger] [--invert] [--quantize INT]
[--fmt-base SYM] [--fmt-quote SYM] [--fmt-time TIME] [--fmt-decimal CHAR] [--fmt-thousands CHAR]
[--fmt-symbol rightspace|right|leftspace|left] [--fmt-datesep CHAR] [--fmt-csvdelim CHAR]
positional arguments:
SOURCE the source identifier
PAIR pair, usually BASE/QUOTE, e.g. BTC/USD
optional arguments:
-h, --help show this help message and exit
-vvv, --verbose show all log messages
-t TYPE, --type TYPE price type, e.g. close
-s DATE, --start DATE start date, inclusive (default: source start)
-sx DATE, --startx DATE start date, exclusive
-e DATE, --end DATE end date, inclusive (default: today)
-ex DATE, --endx DATE end date, exclusive
-o FMT, --output FMT output format (default: csv)
--invert invert the price, swapping base and quote
--quantize INT round to the given number of decimal places
--fmt-base SYM rename the base symbol in output
--fmt-quote SYM rename the quote symbol in output
--fmt-time TIME set a particular time of day in output (default: 00:00:00)
--fmt-decimal CHAR decimal point in output (default: '.')
--fmt-thousands CHAR thousands separator in output (default: '')
--fmt-symbol LOCATION commodity symbol placement in output (default: rightspace)
--fmt-datesep CHAR date separator in output (default: '-')
--fmt-csvdelim CHAR field delimiter for CSV output (default: ',')
```
### Choose and customize the output format
As the output format you can choose one of `beancount`, `csv`, `ledger` or
`gnucash-sql`.
```
pricehist fetch ecb EUR/AUD -s 2021-01-04 -e 2021-01-08 -o ledger
```
```
P 2021-01-04 00:00:00 EUR 1.5928 AUD
P 2021-01-05 00:00:00 EUR 1.5927 AUD
P 2021-01-06 00:00:00 EUR 1.5824 AUD
P 2021-01-07 00:00:00 EUR 1.5836 AUD
P 2021-01-08 00:00:00 EUR 1.5758 AUD
```
Formatting options let you control certain details of the output.
```
pricehist fetch ecb EUR/AUD -s 2021-01-04 -e 2021-01-08 -o ledger \
--fmt-time '' --fmt-datesep / --fmt-base € --fmt-quote $ --fmt-symbol left
```
```
P 2021/01/04 € $1.5928
P 2021/01/05 € $1.5927
P 2021/01/06 € $1.5824
P 2021/01/07 € $1.5836
P 2021/01/08 € $1.5758
```
### Load prices into GnuCash
You can generate SQL for a GnuCash database and apply it immediately with one
of the following commands:
```
pricehist fetch ecb EUR/AUD -s 2021-01-01 -o gnucash-sql | sqlite3 Accounts.gnucash
pricehist fetch ecb EUR/AUD -s 2021-01-01 -o gnucash-sql | mysql -u username -p -D databasename
pricehist fetch ecb EUR/AUD -s 2021-01-01 -o gnucash-sql | psql -U username -d databasename -v ON_ERROR_STOP=1
```
Beware that the GnuCash project itself does not support integration at the
database level, so there is a risk that the SQL generated by `pricehist` will
be ineffective or even damaging for some version of GnuCash.
In practice, this strategy has been used successfully by other projects.
Reading the SQL and keeping regular database backups is recommended.
### Show source information
The `source` command shows information about a source.
```
pricehist source alphavantage
```
```
ID : alphavantage
Name : Alpha Vantage
Description : Provider of market data for stocks, forex and cryptocurrencies
URL : https://www.alphavantage.co/
Start : 1995-01-01
Types : close, open, high, low, adjclose, mid
Notes : Alpha Vantage has data on...
```
Available symbols can be listed for most sources, either as full pairs or as
separate base and quote symbols that will work in certain combinations:
```
pricehist source ecb --symbols
```
```
EUR/AUD Euro against Australian Dollar
EUR/BGN Euro against Bulgarian Lev
EUR/BRL Euro against Brazilian Real
EUR/CAD Euro against Canadian Dollar
EUR/CHF Euro against Swiss Franc
...
```
It may also be possible to search for symbols:
```
pricehist source alphavantage --search Tesla
```
```
TL0.DEX Tesla, Equity, XETRA, EUR
TL0.FRK Tesla, Equity, Frankfurt, EUR
TSLA34.SAO Tesla, Equity, Brazil/Sao Paolo, BRL
TSLA Tesla Inc, Equity, United States, USD
TXLZF Tesla Exploration Ltd, Equity, United States, USD
```
### Inspect source interactions
You can see extra information by adding the verbose option (`--verbose` or
`-vvv`). This will include `curl` commands to reproduce each request to a
source.
```
pricehist fetch coindesk BTC/USD -s 2021-01-01 -e 2021-01-05 -vvv
```
```
DEBUG Began pricehist run at 2021-08-12 14:38:26.630357.
DEBUG Starting new HTTPS connection (1): api.coindesk.com:443
DEBUG https://api.coindesk.com:443 "GET /v1/bpi/historical/close.json?currency=USD&start=2021-01-01&end=2021-01-05 HTTP/1.1" 200 319
DEBUG curl -X GET -H 'Accept: */*' -H 'Accept-Encoding: gzip, deflate' -H 'Connection: keep-alive' -H 'User-Agent: python-requests/2.25.1' --compressed 'https://api.coindesk.com/v1/bpi/historical/close.json?currency=USD&start=2021-01-01&end=2021-01-05'
DEBUG Available data covers the interval [2021-01-01--2021-01-05], as requested.
date,base,quote,amount,source,type
2021-01-01,BTC,USD,29391.775,coindesk,close
2021-01-02,BTC,USD,32198.48,coindesk,close
2021-01-03,BTC,USD,33033.62,coindesk,close
2021-01-04,BTC,USD,32017.565,coindesk,close
2021-01-05,BTC,USD,34035.0067,coindesk,close
DEBUG Ended pricehist run at 2021-08-12 14:38:26.709428.
```
You can run a logged `curl` command to see exactly what data is returned by the
source:
```
pricehist fetch coindesk BTC/USD -s 2021-01-01 -e 2021-01-05 -vvv 2>&1 \
| grep '^DEBUG curl' | sed 's/^DEBUG //' | bash | jq .
```
```json
{
"bpi": {
"2021-01-01": 29391.775,
"2021-01-02": 32198.48,
"2021-01-03": 33033.62,
"2021-01-04": 32017.565,
"2021-01-05": 34035.0067
},
"disclaimer": "This data was produced from the CoinDesk Bitcoin Price Index. BPI value data returned as USD.",
"time": {
"updated": "Jan 6, 2021 00:03:00 UTC",
"updatedISO": "2021-01-06T00:03:00+00:00"
}
}
```
### Use as a library
You may find `pricehist`'s source classes useful in your own scripts:
```
$ python
Python 3.9.6 (default, Jun 30 2021, 10:22:16)
[GCC 11.1.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> from pricehist.series import Series
>>> from pricehist.sources.ecb import ECB
>>> series = ECB().fetch(Series("EUR", "AUD", "reference", "2021-01-04", "2021-01-08"))
>>> series.prices
[Price(date='2021-01-04', amount=Decimal('1.5928')), Price(date='2021-01-05', amount=Decimal('1.5927')), Price(date='2021-01-06', amount=Decimal('1.5824')), Price(date='2021-01-07', amount=Decimal('1.5836')), Price(date='2021-01-08', amount=Decimal('1.5758'))]
```
A subclass of `pricehist.exceptions.SourceError` will be raised for any error.
## Terminology
A **source** is the upstream service that can provide a series of prices.
Each **series** of prices is for one pair and price type.
The [**pair**](https://en.wikipedia.org/wiki/Currency_pair) is made up of a
base and a quote, each given as a symbol. Sometimes you will give the base
only, and the quote will be determined with information from the source. The
available pairs, the symbols used in them and the available price types all
depend on the particular source used.
The **base** is the currency or commodity being valued. Each price expresses
the value of one unit of the base.
The **quote** is the unit used to express the value of the base.
A **symbol** is a code or abbreviation for a currency or commodity.
The **prices** in a series each have a date and an amount.
The **amount** is the number of units of the quote that are equal to one unit
of the base.
Consider the following command:
```
pricehist fetch coindesk BTC/USD --type close
```
- **`coindesk`** is the ID of the CoinDesk Bitcoin Price Index source.
- **`BTC`** is the symbol for Bitcoin.
- **`USD`** is the symbol for the United States Dollar.
- **`BTC/USD`** is the pair Bitcoin against United States Dollar.
- **`close`** is the price type for last price of each day.
A BTC/USD price of the amount 29,391.775 can be written as
"BTC/USD = 29391.775" or "BTC 29391.775 USD", and means that one Bitcoin is
worth 29,391.775 United States Dollars.
## Initial design choices
To keep things simple, `pricehist` provides only univariate time series of
daily historical prices. It doesn't provide other types of market, financial or
economic data, real-time prices, or other temporal resolutions. Multiple or
multivariate series require multiple invocations.
## Future potential features
While the following features are relatively low value or beyond `pricehist`'s
primary use case, they could be built upon the foundation it has established.
- **Time of day**: Sources sometimes provide specific times for each day's
high/low prices and these could be preserved for output. This would require
changes to how dates are handled internally, clarification of time zone
handling and extension of the time formatting option.
- **Alternate resolutions**: Some sources can provide higher or lower
resolution data, such as hourly or weekly. These could be supported where
available. For other cases an option could be provided for downsampling data
before output.
- **Real-time prices**: These generally come from different soruce endpoints
than the historical data. Real-time prices will usually have a different
price type, such as `last`, `bid` or `ask`. Support for real-time prices
would allow adding sources that don't provide historical data. Start and end
times are irrelevant when requesting real-time prices. A "follow" option
could continuously poll for new prices.
- **Related non-price data**: Trading volume, spreads, split and dividend
events and other related data could be supported. The base/quote/type model
used for prices would work for some of this. Other things may require
extending the model.
- **Multivariate series**: Would allow, for example, fetching
high/low/open/close prices in a single invocation.
- **`format` command**: A command for rewriting existing CSV data into one of
the other output formats.
## Alternatives
Beancount's [`bean-price`](https://github.com/beancount/beanprice) tool fetches
prices and addresses other workflow concerns in a Beancount-specific manner,
generally requiring a Beancount file as input.
The [Piecash](https://piecash.readthedocs.io/) library is a pythonic interface
to GnuCash files stored in SQL which has a
[`Commodity.update_prices`](https://piecash.readthedocs.io/en/master/api/piecash.core.commodity.html?highlight=update_prices#piecash.core.commodity.Commodity.update_prices)
method for fetching historical prices.
The GnuCash wiki documents [wrapper scripts](https://wiki.gnucash.org/wiki/Stocks/get_prices)
for the [Finance::QuoteHist](https://metacpan.org/pod/Finance::QuoteHist) Perl
module.