Populate column in data frame based on a range found in another dataframe

Question

I\'m attempting to populate a column in a data frame based on whether the index value of that record falls within a range defined by two columns in another data frame.

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Answer 1

Alternative solution:

---

classdict = df2.set_index("CLASS").to_dict("index")

rangedict = {}

for key,value in classdict.items():

    # get all items in range and assign value (the key)
    for item in list(range(value["START"],value["STOP"]+1)):
        rangedict[item] = key

extract rangedict:

{2: 1, 3: 1, 5: 2, 6: 2, 7: 2, 8: 3}

now map and possibly format(?):

df1['CLASS'] = df1.index.to_series().map(rangedict)
df1.applymap("{0:.0f}".format)

outputs:

a   CLASS
0   4   nan
1   45  nan
2   7   1
3   5   1
4   48  nan
5   44  2
6   22  2
7   89  2
8   45  3
9   44  nan
10  23  nan