CSV stands for Comma Separated Values and CSV files are essentially text files which are used to store data in a tabular fashion using commas (,) as delimiters. CSV is a file format and all the files of this format are stored with a .csv extension. It is a very popular and extensively used format for storing the data in a structured form. CSV files find a lot of applications in Machine Learning and Statistical Models. Python has a library dedicated to deal with operations catering to CSV files such as reading, writing, or modifying them. Following is an example of how a CSV file looks like.
This article deals with the different ways to get column names from CSV files using Python. The following approaches can be used to accomplish the same :
- Using Python’s CSV library to read the CSV file line and line and printing the header as the names of the columns
- Reading the CSV file as a dictionary using DictReader and then printing out the keys of the dictionary
- Converting the CSV file to a data frame using the Pandas library of Python
Method 1:
Using this approach, we first read the CSV file using the CSV library of Python and then output the first row which represents the column names.
Python3
# importing the csv libraryimport csv# opening the csv file by specifying# the location# with the variable name as csv_filewith open('data.csv') as csv_file: # creating an object of csv reader # with the delimiter as , csv_reader = csv.reader(csv_file, delimiter = ',') # list to store the names of columns list_of_column_names = [] # loop to iterate through the rows of csv for row in csv_reader: # adding the first row list_of_column_names.append(row) # breaking the loop after the # first iteration itself break# printing the resultprint("List of column names : ", list_of_column_names[0]) |
Output:
List of column names : ['Column1', 'Column2', 'Column3']
Method 2:
Under the second approach, we use the DictReader function of the CSV library to read the CSV file as a dictionary. We can simply use keys() method to get the column names.
Steps :
- Open the CSV file using DictReader.
- Convert this file into a list.
- Convert the first row of the list to the dictionary.
- Call the keys() method of the dictionary and convert it into a list.
- Display the list.
Python3
# importing the csv libraryimport csv# opening the csv filewith open('data.csv') as csv_file: # reading the csv file using DictReader csv_reader = csv.DictReader(csv_file) # converting the file to dictionary # by first converting to list # and then converting the list to dict dict_from_csv = dict(list(csv_reader)[0]) # making a list from the keys of the dict list_of_column_names = list(dict_from_csv.keys()) # displaying the list of column names print("List of column names : ", list_of_column_names) |
Output :
List of column names : ['Column1', 'Column2', 'Column3']
Method 3:
Under this approach, we read the CSV file as a data frame using the pandas library of Python. Then, we just call the column’s method of the data frame.
Python3
# importing the pandas libraryimport pandas as pd# reading the csv file using read_csv# storing the data frame in variable called dfdf = pd.read_csv('data.csv')# creating a list of column names by# calling the .columnslist_of_column_names = list(df.columns)# displaying the list of column namesprint('List of column names : ', list_of_column_names) |
Output :
List of column names : ['Column1', 'Column2', 'Column3']
The Data Frame looks as follows :
The CSV file as a Data Frame
