Float values as dictionary key

Another way would be enter the keys as strings with the point rather than a p and then recast them as floats for plotting.

Personally, if you don't insist on the dict format, I would store the data as a pandas dataframe with the pH as a column as these are easier to pass to plotting libraries

There's no problem using floats as dict keys.

Just round(n, 1) them to normalise them to your keyspace. eg.

>>> hash(round(6.84, 1))
3543446220
>>> hash(round(6.75, 1))
3543446220

Perhaps you want to truncate your float prior to using is as key?

Maybe like this:

a = 0.122334
round(a, 4)       #<-- use this as your key?

Your key is now:

0.1223           # still a float, but you have control over its quality

You can use it as follows:

dictionary[round(a, 4)]   

to retrieve your values