Get the index from an specific value in a panda Dataframe

Question

I'm looking for a way to get the row index from an specific entry in that's in a column of the Dataframe. I need it so that the I can use that index to get the whole row where that entry is. I have achieved to get the value I'm looking for in the column but I'm unable to get its index. Here's my code so far:

import glob, os
from pandas import *
filepath = r'C:\Users\Dani\Documents\clase dani\PhD\GC\Cuanti'
for csv_file in glob.glob(os.path.join(filepath, '*.csv')):
    rt=pandas.read_csv(csv_file, skiprows=6)
    rt.set_index('Peak')
    RTlist=rt.loc[:,'R.T.']
    for item in RTlist:
        if 5.5<item<5.8:
            #here's where I want to get the row index where item is at, but I can't achieve it. 

Thanks for your help.

Answer 1

Making use of iteritems to loop through the Series RTlist, might be what you're looking for

for index, item in RTlist.iteritems():
    if 5.5<item<5.8:
        item_index = index
        item_value = item

Answer 2

For demonstration purpose I created the source DataFrame ( rt ) as follows:

rt = pd.DataFrame([ [ 1, 2, 5 ], [ 2, 5, 6 ], [ 3, 5.52, 7 ], [ 4, 5.6, 8 ],
    [ 5, 5.75, 9 ], [ 6, 5.8, 10 ], [ 7, 6, 11 ] ],
    columns=[ 'Peak', 'R.T.', 'Xxx' ])
rt.set_index('Peak')

You can get the result (index / value pairs) with a single instruction:

rt['R.T.'][rt['R.T.'].between(5.5, 5.8, inclusive=False)]

For my test data it prints:

2    5.52
3    5.60
4    5.75

rt['RT'] selects a whole 'RT' column.

Then [rt['RT'].between(5.5, 5.8, inclusive=False)] is a predicate, selecting values in the specified range.

Or maybe you are interested in index values only ? If this is the case, write:

rt[rt['R.T.'].between(5.5, 5.8, inclusive=False)].index