Check for a specific value in pandas dataframe column

Question

I am trying to retrieve the value in A if the value of B is 1. But the below code throws the error "ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()"

    A   B
0   a1  18
1   b1  25229
2   c2  2
3   d3  12
4   e4  1

Code:

for a,b in df7.iteritems():
  if (df7['b'] == 1):
    print (df7['a'])

You wouldn't do for a,b in df7.iteritems(): and then try to reference the columns by df7['a'], df7['b'], that will return you the entire column. — smci
– smci, Commented Apr 21, 2019 at 10:42

Jan · Accepted Answer · 2018-02-23 17:22:43Z

5

You could use a simple comparison like

import pandas as pd

df = pd.DataFrame({'A': ['a1', 'b1', 'c2', 'd3', 'e4'], 'B': [18, 25229, 2, 12, 1]})
print(df[df['B'] == 1]['A'])

Which yields

4    e4
Name: A, dtype: object

answered Feb 23, 2018 at 17:22

Jan

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1 Comment

mLstudent33 Over a year ago

how would I just get e4 and not '4'?

Shahir Ansari · Accepted Answer · 2019-09-24 08:06:48Z

0

Another simple code would be

df7[df7['b'] == 1]['a']

will give a dataframe of column a where b=1.

answered Sep 24, 2019 at 8:06

Shahir Ansari

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