Download¶

As a software, IOSACal is still in its infancy. The 0.1 version will be released soon, but in the meantime you can get the development version from bitbucket, either with the complete project history or as a simple source archive.

Installing¶

Just extract the downloaded archive, move to the main directory and:

python setup.py install

from the main directory. Using pip and virtualenv is strongly recommended.

After the install has completed, the iosacal binary will be available.

Command line options¶

IOSACal works from the command line. These are the available options.

-h¶

Show an help message and exit

-d <date>, --date=<date>¶

Non-calibrated radiocarbon BP date for the sample

-s <sigma>, --sigma=<sigma>¶

Standard deviation for the non-calibrated date given with the above option

-c <curve>, --curve=<curve>¶

Calibration curve to be used [default: intcal09]

If you want to specify a different calibration curve provide the curve canonical name in lower case (e.g. intcal09, marine09).

-i, --interpolate¶

Interpolate calibration curve to obtain fine-grained dating intervals [default: False]

-n <name>, --name=<name>¶

Name of sample, used also for output image [default: iosacal]

Basic usage¶

The command line program is called iosacal. It can generate both text output and image plots.

The typical usage is:

iosacal -d 790 -s 60

Output will look like the following:

==============
 IOSACal v0.1
==============

Atmospheric data from Reimer et al (2009);

Radiocarbon determination (BP): 790 ± 60 BP

Calibrated date
---------------

68.2% probability
 BP 760 ‒ BP 755 (5.2 %)
 BP 740 ‒ BP 675 (61.2 %)

95.4% probability
 BP 900 ‒ BP 865 (4.6 %)
 BP 825 ‒ BP 815 (1.4 %)
 BP 800 ‒ BP 655 (88.9 %)

If you want an image instead of text output, just add the -p flag:

iosacal -d 790 -s 60 -p

The result will be saved into the image file named iosacal_790±60.pdf in the same directory. It will look more or less like this:

Other calibration curves¶

By default, iosacal uses the IntCal09 calibration curve. IOSACal is however able to read any calibration curve that uses the same format as intcal09.14c, like those available on <http://www.radiocarbon.org/>. If you want to specify a different calibration curve provide the curve canonical name in lower case (e.g. intcal09, marine09).

To specify a calibration curve, use the -c command line option:

iosacal -d 790 -s 60 -p -c marine09

Interpolation¶

The standard IntCal09 calibration curve has a varying resolution: data spacing changes from 5 years for the range from 0 to 11.2 to cal kBP, 10 yrs for 11.2–15 cal kBP, 20 yrs for 15–25 cal kBP, 50 yrs for 25–40 cal kBP, and 100 yrs for 40–50 cal kBP [REI2009].

This means that the output intervals will follow these limitations. It’s possible to use linear interpolation to get more fine-grained results, particularly concerning probability intervals.

Use the -i flag to activate interpolation:

iosacal -d 790 -s 60 -p --ad -i

IOSACal makes use of the SciPy library for interpolating calibration curves. Even if SciPy is not required for IOSACal’s normal usage and interpolation is disabled by default, installing SciPy is recommended.

Multiple dates¶

It is also possible to give IOSACal more than one radiocarbon determination, to see how 2 or more samples relate between themselves.

To use the multiple dates feature, just pass more -d and -s options on the command line:

iosacal -d 790 -s 60 -d 917 -s 55 -d 1005 -s 45 -p

The order in which values are passed to IOSACal matters, so the first date will be matched to the first standard deviation and so on.

This way, you will get 3 different single plots. If you want to obtain also a compound plot, add the -m flag:

iosacal -d 790 -s 60 -d 917 -s 55 -d 1005 -s 45 -p -m

It’s also useful to use the -n option to give a name to the image, and also a title to the plot:

iosacal -d 790 -s 60 -d 917 -s 55 -d 1005 -s 45 -p -m -n "Donetta"