Pandas Function returning "None" instead of DataFrame

Question

My Pandas function is returning "None" as a result instead of the DataFrame that I am trying to filter using the function that I have written. Why is this so? And how can I resolve this? Thank you!

import pandas as pd
nz_data = pd.read_csv('research-and-development-survey-2016-2019-csv.csv', index_col = 2)

def count_of_mining_biz():
    if "B_Mining" in nz_data[["Breakdown_category"]] and "Count of businesses" in nz_data[["Units"]]:
        return nz_data.loc["2019", "RD_Value"]

print(count_of_mining_biz())

Here is how the data looks like.

I am trying to find out the RD Value in 2019 for the Mining industry. The reason why I have to set a conditional for the "Units" column is because there is another type of data that is not the count for the business mentioned.

tdy · Accepted Answer · 2021-05-02 10:10:22Z

2

.loc[..., ...] means .loc[row_index, col_index] but there's no row index called 2019.

Try using .loc with boolean masks in this case:

def count_of_mining_biz():
    category = nz_data['Breakdown_category'] == 'B_Mining'
    units = nz_data['Units'] == 'Count of businesses'
    year = nz_data['Year'] == 2019
    return nz_data.loc[category & units & year].RD_Value

edited May 2, 2021 at 10:10

answered May 2, 2021 at 9:58

tdy

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7 Comments

pleepc Over a year ago

Hi Geof, thank you for your help! I encountered an error that says: KeyError: 'Year'. How can I resolve it?

tdy Over a year ago

@pleepc can you copy-paste the output of print(nz_data.columns)

pleepc Over a year ago

hey Geof, here's the output: Index(['Variable', 'Breakdown_category', 'RD_Value', 'Units'], dtype='object'). However, even after I removed "Year" as my index_col, the output of print(count_of_mining_biz()) gives me: Series([], Name: RD_Value, dtype: object). Am I doing something wrong here?

tdy Over a year ago

@pleepc (1) If Year is a str instead of int, it needs quotes like '2019' instead of just 2019, so check the output of print(type(df.iloc[0].Year)) to see which it is. (2) Units and Breakdown_category might have leading/trailing spaces, so strip() them first just in case (and if Year ends up being a str, then strip() it too):

nz_data['Units'] = nz_data['Units'].str.strip(); nz_data['Breakdown_category'] = nz_data['Breakdown_category'].str.strip()

pleepc Over a year ago

hey Geof, thank you so much, it works now after I removed the 'index_col = 2' argument. I managed to get the correct answer, which is '3', however, python returns me another number before that, so I am getting '5 3'. Do you mind explaining why does it have the '5' in front?

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