Is there a way to print a dataframe to a log file with columns aligned?

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I'm trying to print a data frame to a log file, but the columns are misaligned. I came up with this solution to get the dataframe columns and row as a list, and then convert the columns and floating point data to strings, but there must be a better way to do this.

       logging.error(f'Quality Metrics for Reconstructed File are Lower than Reference!!!')

       print(df.shape)
       columns = df_res.columns
       msg = ' '.join(columns)
       print(msg)
       logging.error(msg)

       data = df_res.iloc[0,:].tolist()
       msg = '   '.join(map(str, data))
       print(msg)
       logging.error(msg)```

This is what the log file looks like.

2022-08-24 16:03:49,084 [ERROR] mse_avg mse_r mse_g mse_b psnr_avg psnr_r psnr_g psnr_b
2022-08-24 16:03:51,263 [ERROR] 0.02   0.01   0.03   0.01   65.44   67.82   62.78   67.82

You can see that the columns are not aligned correctly. Any advice on a better way to do this so that my log output is properly formatted?
pandas dataframe logging python string
2 Answers

This example is using str.format to properly format column header and values from first row of dataframe:

max_column_len = len(max(df.columns, key=len))
fmt = "{{:>{}}}  ".format(max_column_len) * len(df.columns)

columns = fmt.format(*df.columns)
first_row = fmt.format(*df.iloc[0])

print(columns)    # <--- you can use `columns` in your logging function
print(first_row)  # <--- ...

Prints:

 mse_avg     mse_r     mse_g     mse_b  psnr_avg    psnr_r    psnr_g    psnr_b  
    0.02      0.01      0.03      0.01     65.44     67.82     62.78     67.82

Dataframe used:

   mse_avg  mse_r  mse_g  mse_b  psnr_avg  psnr_r  psnr_g  psnr_b
0     0.02   0.01   0.03   0.01     65.44   67.82   62.78   67.82

Another solution:

# convert dataframe string and then split it:
for line in str(df).splitlines():
    print(line)
user_100359850

You could use this pandas method:

string = df.to_csv(sep='\t')

It will separate the entries with a tabulator, which should appear aligned in most text editors.

user_193142840
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