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

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?

CodePudding user response：

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)

CodePudding user response：

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.