Feature: Workaround for missing MFD data points

[chrisbc]

in https://github.com/GNS-Science/nzshm-opensha/issues/231 @chrisdicaprio describes a problems where our dynamic MFD plots are not matching the PNG versions from opensha.

The example given is http://simple-toshi-ui-test.s3-website-ap-southeast-2.amazonaws.com/InversionSolution/SW52ZXJzaW9uU29sdXRpb246MTAwMzkw

It looks like the problem is missing values in the source data (see comments on above issue). This can be fixed at source (in opensha) but it won't correct anything retrospectively. This ticket provides a simple TUI workaround which works immediatlye and retrospectively....

• [ ] In our TUI dynamic MFD plot, we want to set all graph points to have a default minimum value (e.g. 1e-20)
• [ ] when a MFD table has missing values (as per above) the value for that point will be the default min.
• [ ] the plot should now resemble

[chrisbc]

Notes from @benjamineac talk...

Context: MFD plots consist or one or more sereis, each series will have centres at regular intervals of 0.1

So we can safely assume: start 5.05 .., end 9.95, fill everything between at 0.1 intervals with default 1e-20

draft algorthm for each MFD series:

• retrieve API data = [(5.05, 0.1), [?missing?,] (5.25, x), ....]
• default = [(5.05, 1e-20), (5.15, 1e-20), (5.25, 1e-20) ...... (9.95, 1e-20)] since we expect points at regular intervals! then simply merge default & data.

API table result....

table: "MFD table" 
columns: [series ID, seriesName, X, Y], 
types: 

rows: [
    “0”, “targetOnFaultSupraSeisMFD”, “5.05”, “1.0E-20"
    “0”, “targetOnFaultSupraSeisMFD”, “5.15”, “1.0E-20"
    “0”, “targetOnFaultSupraSeisMFD”, “5.35”, “1.0E-20"
    “0”, “targetOnFaultSupraSeisMFD”, “5.45”, “1.0E-20"
    “0”, “targetOnFaultSupraSeisMFD”, “5.55”, “1.0E-20"
    “1”, “SeriesB”, “5.45”, “1.0E-20"
    “1”, “SeriesB”, “5.45”, “1.0E-20"
    “1”, “SeriesB”, “5.45”, “1.0E-20"
    “1”, “SeriesB”, “5.45”, “1.0E-20"
]