Float values as dictionary key

Question

I am developing a class for the analysis of microtiter plates. The samples are described in a separate file and the entries are used for an ordered dictionary. One of the ke

Answer 1

Another option would be to use tuples:

dictionary = {(6.8,): 0.3985}
dictionary[(6.8,)]

Then Retrieving the values later for plotting is easily done with something like

points = [(pH, value) for (pH,), value in dictionary.items()]
    ...

Answer 2

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

Answer 3

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

Answer 4

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

Answer 5

Another quick option is to use strings of the float

a = 200.01234567890123456789
b = {str(a): 1}
for key in b:
    print(float(key), b[key])

would print out

(200.012345679, 1)

notice a gets truncated at tenth digit after decimal point.