If statement nested in For loop - Getting error = The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()

Question

I am trying to write a if statement nested in a for loop for my data frame, which looks like the below:

I want the code to iterate through each row of the dataframe and if it detects "CV22" in the column Detection_Location, it should import one file as dataframe and if it detects "CV23" in column Detection_location, it should import another file as the same dataframe as earlier.

I have tried writing the below code for doing this:

def Get_PHD(df2):
    if (df2['Detection_Location'] == 'CV22'):
           PHD_df = pd.read_excel(r'C:\Users\s.gaur\Desktop\LS1 - Edited file.xlsx', sheet_by_name = "Sheet1")
           return (PHD_df)
    elif (df2['Detection_Location'] == 'CV23'):
           PHD_df = pd.read_excel(r'C:\Users\s.gaur\Desktop\LS2 - Edited File.xlsx', sheet_by_name = "Sheet1")
           return (PHD_df)



for index, row in df2.iterrows():
    Get_PHD(df2)

But getting the following error:

The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().

Can anyone please help as in what I am doing wrong.

Screenshots of data aren't that helpful for reproducing; [Provide a copy of the DataFrame](https://stackoverflow.com/questions/52413246/how-do-i-provide-a-reproducible-copy-of-my-existing-dataframe) — Trenton McKinney, Aug 16 '19 at 00:15
@Trenton_M - The dataset is actually as small as visible in the picture. There is nothing more to it actually. — zsh_18, Aug 16 '19 at 01:45

score 0 · Answer 1 · answered Aug 16 '19 at 00:16

0

THis is not a valid Boolean expression:

if (df2['Detection_Location'] == 'CV22'):

df2['Detection_Location'] is a column of data, not an atomic element. Thus, the if cannot be accurately evaluated as either True or False. Hence your error message.

answered Aug 16 '19 at 00:16

Prune

76,765
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60
81

score 0 · Answer 2 · answered Aug 16 '19 at 00:17

0

In a for loop that you have you pass DataFrame to Get_PHD function, so the part df2['Detection_Location'] == 'CV22' is a Series with boolean values.

Just change the loop to:

for index, row in df2.iterrows():
    Get_PHD(row)

answered Aug 16 '19 at 00:17

puchal

1,883
13
25

score 0 · Accepted Answer · answered Aug 16 '19 at 00:18

Try passing the row to the Get_PHD function and calling the Detection_Location from the row:

def Get_PHD(row):
    if (row.Detection_Location == 'CV22'):
           PHD_df = pd.read_excel(r'C:\Users\s.gaur\Desktop\LS1 - Edited file.xlsx', sheet_by_name = "Sheet1")
           return (PHD_df)
    elif (row.Detection_Location == 'CV23'):
           PHD_df = pd.read_excel(r'C:\Users\s.gaur\Desktop\LS2 - Edited File.xlsx', sheet_by_name = "Sheet1")
           return (PHD_df)


for index, row in df2.iterrows():
    Get_PHD(row)

Trenton McKinney · Answer 4 · 2019-08-16T00:56:27.533

def Get_PHD(row):
    value = row.Detection_Location
    states = {'CV22': {'file': r'C:\Users\s.gaur\Desktop\LS1 - Edited file.xlsx', 'sheet': 'Sheet1'},
              'CV23': {'file': r'C:\Users\s.gaur\Desktop\LS2 - Edited File.xlsx', 'sheet': 'Sheet1'}}

    try:
        return pd.read_excel(states[value]['file'], states[value]['sheet'])
    except (KeyError, FileNotFoundError) as e:
        print(e)

for _, row in df2.iterrows():
    Get_PHD(row)  # the code example has df2 here, not row

try, except is included on the possibility you're dealing with more conditions that stated.
- if you miss a Detection_Location or if the file path is incorrect, the code will notify you
this code is more efficient in that new locations only need to be added to states

If statement nested in For loop - Getting error = The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all()

4 Answers4