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

import pandas as pd
import numpy as np

# Here is your existing dataframe
df_existing = pd.DataFrame(np.random.randint(0,100,size=(100, 4)), columns=list('ABCD'))

# Create a new empty dataframe with specific column names and data types
df_new = pd.DataFrame(index=None)
columns = ['field01','field02','field03','field04']
dtypes = [str,int,int,int]
for c,d in zip(columns, dtypes):
    df_new[c] = pd.Series(dtype=d)

# Set the index on the new dataframe to same as existing 
df_new['new_index'] = df_existing.index
df_new.set_index('new_index', inplace=True)

# Fill the new dataframe with specific fields from the existing dataframe
df_new[['field02','field03']] = df_existing[['B','C']]
print df_new