pandas DataFrame output end of csv
Thank to Andy, the complete solution:
f = open(filename, 'a') # Open file as append mode
df.to_csv(f, header = False)
f.close()
You can also pass the file mode as an argument to the to_csv method
df.to_csv(file_name, header=False, mode = 'a')
You can append using to_csv
by passing a file which is open in append mode:
with open(file_name, 'a') as f:
df.to_csv(f, header=False)
Use header=None
, so as not to append the column names.
In fact, pandas has a wrapper to do this in to_csv
using the mode
argument (see Joe's answer):
df.to_csv(f, mode='a', header=False)
A little helper function I use (based on Joe Hooper's answer) with some header checking safeguards to handle it all:
def appendDFToCSV_void(df, csvFilePath, sep=","):
import os
if not os.path.isfile(csvFilePath):
df.to_csv(csvFilePath, mode='a', index=False, sep=sep)
elif len(df.columns) != len(pd.read_csv(csvFilePath, nrows=1, sep=sep).columns):
raise Exception("Columns do not match!! Dataframe has " + str(len(df.columns)) + " columns. CSV file has " + str(len(pd.read_csv(csvFilePath, nrows=1, sep=sep).columns)) + " columns.")
elif not (df.columns == pd.read_csv(csvFilePath, nrows=1, sep=sep).columns).all():
raise Exception("Columns and column order of dataframe and csv file do not match!!")
else:
df.to_csv(csvFilePath, mode='a', index=False, sep=sep, header=False)