Presolar Grains
The presolar grain class is the meat of pgdtools and likely the class you will use the most.
There are two ways to get the full database:
or
We recommend the latter method, as it is shorter.
Examples for usage can be found in the Examples menu on the left.
Filtering
One of the main features of pgdtools is that it allows you to filter the database.
Details on all the possible filters can be found
here.
The following would filter the database to only show Graphite grains that have 12C/13C ratios greater than 100 and uncertainties on these ratios of less than 1.0.
from pgdtools import pgd
ratio = ("12C", "13C") # let's define the ratio once
pgd.filter.db(pgd.DataBase.Graphite)
pgd.filter.ratio(ratio, "<", 100)
pgd.filter.uncertainty(ratio, "<", 1.0)
At any point, you can reset the database to incldue all grains and start over.
To do so, use pgd.reset().
Data retrieval
After filtering, you might want to retreive the data. Details on all the possible data retrieval methods can be found here.
As an example, let's say you want to plot the 12C/13C versus the 14N/15N ratios of the grains you have filtered.
from pgdtools import pgd
x_ratio = ("12C", "13C")
y_ratio = ("14N", "15N")
# do your filtering here
xdat, xunc, ydat, yunc, corr = pgd.data.ratio_xy(x_ratio, y_ratio)
If you only want to retrieve the data for one isotope ratios (plus the uncertainties),
check out the routine pgd.data.ratio(...).
Formatting helper functions
In order to create beautiful plots, pgdtools provides a few helper functions.
As you have seen above, a ratio tuple is all you need to get an isotopic ratio or a delta-value of an isotopic ratio
from the data retrieval functions.
You can use the same tuple to directly get a nicely formatted label for your plot!
This will provide you with a LaTeX formatted string that you can,
e.g., directly pass to matplotlib as an axis label.
References
If you are using pgdtools for a publication,
you might want to know who measured the original data.
We provide easy access to the references with the pgd.reference property.
This will act on your filtered database.
A full list of properties and methods can be found
here.
You can, e.g., print this property directly or just get the DOIs of the references.
This will return a set of DOIs that you can use further, i.e., to import into your reference manager.
Techniques
Similar to the references, pgdtools exposes the techniques section of the database to the user.
A full list of features can be found
here.
As an example, you can get a dataframe with a set of all the techniques used for your filtered dataset:
Information
Finally, pgdtools also comes with an info property that allows you to search the database.
While the properties technique and reference also provide you with information,
these two sections are actual tables/sheets in the Excel version of the database.
The info property on the other hand lets you explore the database and allows you,
e.g., to find isotope ratios that are available in the database itself.
Details on all the functionality can be found
here.
As an example, let's say you want to find out what Ru isotopic ratios are available in the database:
This will print out all the Ru isotopic ratios, but also return a list of tuples in which you find first the ratio header and second if this ratio is a delta value. The printed information, as an example, is as following: