熊猫在将DataFrame导出到CSV时如何保持LAST尾随零

Question

In this question, my goal is to preserve the last trailing zeros when exporting the DataFrame to CSV

My dataset looks like this:

EST_TIME    Open    High
2017-01-01  1.0482  1.1200    
2017-01-02  1.0483  1.1230
2017-01-03  1.0485  1.0521
2017-01-04  1.0480  1.6483
2017-01-05  1.0480  1.7401
...., ...., ....
2017-12-31  1.0486  1.8480

I import and create a DataFrame and save to CSV by doing this:

df_file = '2017.csv'
df.to_csv(df_file, index=False)
files.download(df_file)

When I view the CSV, I see this:

EST_TIME    Open    High
2017-01-01  1.0482  1.12   
2017-01-02  1.0483  1.123
2017-01-03  1.0485  1.0521
2017-01-04  1.048   1.6483
2017-01-05  1.048   1.7401
...., ...., ....
2017-12-31  1.0486  1.848

All the zeros at the end are gone. I want to preserve the trailing zeros when I save the CSV and I want it at 4 decimal place.

Could you please let me know how can I achieve this?

Answer 1

You could call apply and use format as such before writing to csv:

df_file = '2017.csv'
df['Open'] = df['Open'].apply('{:0<6}'.format)
df['High'] = df['High'].apply('{:0<6}'.format)
df.to_csv(df_file, index=False)

To apply to all columns, you can use applymap :

df = df.applymap('{:0<6}'.format)

Hope this helps.

Answer 2

Try this: Float format both to display your data with 4 decimal places and to save it with 4 decimal.

when reading to pandas:

pd.options.display.float_format = '{:,.4f}'.format

when saving to CSV.

df.to_csv('your_file.csv', float_format='%.4f',index=False)