Python 3.x - Append data to Pandas dataframe using for loop

Question

I have a empty pandas DataFrame:

aqi_df = pd.DataFrame(columns = ["IMEI","Date","pm10conc_24hrs","pm25conc_24hrs","sdPm10","sdPm25","aqi","windspeed","winddirection","severity","health_impact"] )

I want to add elements one by one to each column -

for i in range(1,10):
   aqi_df.IMEI.append("a")
   aqi_df.Date.append("b")
   aqi_df.pm10conc_24hrs.append("c")
   .
   .
   .

But append throws an error

TypeError: cannot concatenate a non-NDFrame object

How can I append elements to pandas dataframe one by one?

The error is clear, you need to pass a Series or a DataFrame for appending, besides why do this when it's non-performant as you'll iteratively grow the df on each append call so it'll be slow — EdChum
– EdChum, Commented Jun 13, 2016 at 9:07

jezrael · Accepted Answer · 2016-06-13 09:14:24Z

1

IIUC you can use:

aqi_df = pd.DataFrame(columns = ["IMEI","Date","pm10conc_24hrs"] )
print (aqi_df)


for i in range(1,10):
   aqi_df.loc[i] = ['a','b','c']

print (aqi_df)
  IMEI Date pm10conc_24hrs
1    a    b              c
2    a    b              c
3    a    b              c
4    a    b              c
5    a    b              c
6    a    b              c
7    a    b              c
8    a    b              c
9    a    b              c

But better is creating DataFrame from Series or dict:

IMEI = pd.Series(['aa','bb','cc'])
Date = pd.Series(['2016-01-03','2016-01-06','2016-01-08'])
pm10conc_24hrs = pd.Series(['w','e','h'])

aqi_df = pd.DataFrame({'a':IMEI,'Date':Date,'pm10conc_24hrs':pm10conc_24hrs})
print (aqi_df)
         Date   a pm10conc_24hrs
0  2016-01-03  aa              w
1  2016-01-06  bb              e
2  2016-01-08  cc              h

aqi_df = pd.DataFrame({'a':['aa','bb','cc'],
                       'Date':['2016-01-03','2016-01-06','2016-01-08'],
                       'pm10conc_24hrs':['w','e','h']})
print (aqi_df)
         Date   a pm10conc_24hrs
0  2016-01-03  aa              w
1  2016-01-06  bb              e
2  2016-01-08  cc              h

edited Jun 13, 2016 at 9:14

answered Jun 13, 2016 at 9:09

jezrael

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1 Comment

Rohan Bapat Over a year ago

Thanks for the suggestion @jezrael

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