Python - Operations in Pandas Dataframe-CodePudding

I have this dataframe which is read from an excel file:

I want to know the value of a given column, apply rules, then update it. I'm trying this:

ticker='BTCUSDT'
print(df.at[ticker,'Position'])

#Then, I want to update that value:

df.at[ticker,'Position']=1

When i do this, i get a Key Error. In this example: KeyError: 'BTCUSDT'

Expected:

print=0
cell after assign = 1

This works, however, if I first assign a value to the cell, in example:

if first i do this:

ticker='BTCUSDT'
df.at['BTCUSDT','Position']=0
#then this works:

ticker='BTCUSDT'
df.at[ticker,'Position']

df.at[ticker,'Position']=1

What am I doing wrong ?

Thanks in advance.

CodePudding user response：

Ticker is not the Index but just a column. If you do df = df.set_index('Ticker') yoi should be good

CodePudding user response：

The following code will look for the ticker value BTCUSDT within the Ticker column,
and change the value in the associated Position column to 1.

Code:

ticker='BTCUSDT'
df.loc[df['Ticker'] == ticker, 'Position'] = 1

For example:

If you have the following dataframe:

df = pd.DataFrame({ 'Ticker': ['BTCBUSD', 'ETHBUSD', 'LTCBUSD', 'SOLBUSD', 'FIMUSDT'],
                    'Position': [0,0,0,0,0],
                    'Quantity': [0,0,0,0,0],
                    'Price':[0,0,0,0,0]})

You can update the position value of BTCBUSD to 1 in the same way using:

ticker='BTCBUSD'
df.loc[df['Ticker'] == ticker, 'Position'] = 1
print(df)

Code:

For example:

Output: