How do i read a csv cell value in python?
Following the comments to the SO question here, a best, more robust code would be: Show
Update: If what the OP actually wants is the last string in the last row of the csv file, there are several aproaches that not necesarily needs csv. For example,
This is not good for very big files because you load the
complete text in memory but could be ok for small files. Note that And finally if what the OP wants is the second string in line n (for n=2): Update 2: This is now the same code than the one in the answer from J.F.Sebastian. (The credit is for him): What is a CSV file?A CSV file is a simple type of plain text file which uses a specific structure to arrange tabular data. The standard format of a CSV file is defined by rows and columns data where a newline terminates each row to begin the next row, and each column is separated by a comma within the row. CSV is a common format for data interchange as it is compact, simple, and general. Many online services allow their users to export tabular data from the website into a CSV file. Files of CSV will open into Excel, and nearly all databases have a tool to allow import from CSV files. In this tutorial, you will learn:
CSV Sample FileData in the form of tables is also called CSV (comma separated values) – literally “comma-separated values.” This is a text format intended for the presentation of tabular data. Each line of the file is one line of the table. The values of individual columns are separated by a separator symbol – a comma (,), a semicolon (;) or another symbol. CSV can be easily read and processed by Python. Consider the following Table Table Data
You can represent this table in csv as below. CSV DataProgramming language, Designed by, Appeared, Extension Python, Guido van Rossum, 1991, .py Java, James Gosling, 1995, .java C++, Bjarne Stroustrup,1983,.cpp As you can see each row is a new line, and each column is separated with a comma. This is an example of how a CSV file looks like. Download CSV Data Python provides a CSV module to handle CSV files. To read/write data, you need to loop through rows of the CSV. You need to use the split method to get data from specified columns. CSV Module FunctionsIn CSV module documentation you can find following functions:
In this tutorial, we are going to focus only on the reader and writer functions which allow you to edit, modify, and manipulate the data in a CSV file. How to Read a CSV File in PythonBelow are steps to read CSV file in Python. Step 1) To read data from CSV files, you must use the reader function to generate a reader object. The reader function is developed to take each row of the file and make a list of all columns. Then, you have to choose the column you want the variable data for. It sounds a lot more intricate than it is. Let’s take a look at this Python code to read CSV file, and we will find out that working with csv file isn’t so hard. #import necessary modules import csv with open('X:\data.csv','rt')as f: data = csv.reader(f) for row in data: print(row) Step 2) When you execute the program above, the output will be: ['Programming language; Designed by; Appeared; Extension'] ['Python; Guido van Rossum; 1991; .py'] ['Java; James Gosling; 1995; .java'] ['C++; Bjarne Stroustrup;1983;.cpp'] How to read a CSV file into a Dictionary in PythonYou can also you use DictReader to read CSV files. The results are interpreted as a dictionary where the header row is the key, and other rows are values. Consider the following code #import necessary modules import csv reader = csv.DictReader(open("file2.csv")) for raw in reader: print(raw) The result of this code is: OrderedDict([('Programming language', 'Python'), ('Designed by', 'Guido van Rossum'), (' Appeared', ' 1991'), (' Extension', ' .py')]) OrderedDict([('Programming language', 'Java'), ('Designed by', 'James Gosling'), (' Appeared', ' 1995'), (' Extension', ' .java')]) OrderedDict([('Programming language', 'C++'), ('Designed by', ' Bjarne Stroustrup'), (' Appeared', ' 1985'), (' Extension', ' .cpp')]) And this way to read data from CSV file is much easier than earlier method. However, this is not isn’t the best way to read data. How to write CSV File in PythonHere is how to write a CSV file in Python: When you have a set of data that you would like to store in a CSV file you have to use writer() function. To iterate the data over the rows(lines), you have to use the writerow() function. Consider the following example. We write data into a file “writeData.csv” where the delimiter is an apostrophe. #import necessary modules import csv with open('X:\writeData.csv', mode='w') as file: writer = csv.writer(file, delimiter=',', quotechar='"', quoting=csv.QUOTE_MINIMAL) #way to write to csv file writer.writerow(['Programming language', 'Designed by', 'Appeared', 'Extension']) writer.writerow(['Python', 'Guido van Rossum', '1991', '.py']) writer.writerow(['Java', 'James Gosling', '1995', '.java']) writer.writerow(['C++', 'Bjarne Stroustrup', '1985', '.cpp']) Result in csv file is: Programming language, Designed by, Appeared, Extension Python, Guido van Rossum, 1991, .py Java, James Gosling, 1995, .java C++, Bjarne Stroustrup,1983,.cpp Read CSV File using PandasPandas is an opensource library that allows to you import CSV in Python and perform data manipulation. Pandas provide an easy way to create, manipulate and delete the data. You must install pandas library with command Reading the CSV into a pandas DataFrame is very quick and easy: #import necessary modules import pandas result = pandas.read_csv('X:\data.csv') print(result) Result of the read CSV Pandas example: Programming language, Designed by, Appeared, Extension 0 Python, Guido van Rossum, 1991, .py 1 Java, James Gosling, 1995, .java 2 C++, Bjarne Stroustrup,1983,.cpp Very useful library. In just three lines of code you the same result as earlier. Pandas know that the first line of the CSV contained column names, and it will use them automatically. Write CSV File using PandasWriting to CSV file with Pandas is as easy as reading. Here you can convince in it. First you must create DataFrame based on the following Python write to CSV code. from pandas import DataFrame C = {'Programming language': ['Python','Java', 'C++'], 'Designed by': ['Guido van Rossum', 'James Gosling', 'Bjarne Stroustrup'], 'Appeared': ['1991', '1995', '1985'], 'Extension': ['.py', '.java', '.cpp'], } df = DataFrame(C, columns= ['Programming language', 'Designed by', 'Appeared', 'Extension']) export_csv = df.to_csv (r'X:\pandaresult.csv', index = None, header=True) # here you have to write path, where result file will be stored print (df) Here is the output Programming language, Designed by, Appeared, Extension 0 Python, Guido van Rossum, 1991, .py 1 Java, James Gosling, 1995, .java 2 C++, Bjarne Stroustrup,1983,.cpp And CSV file is created at the specified location. ConclusionSo, now you know how use method ‘csv’ and also read and write data in CSV format. CSV files are widely used in software applications because they are easy to read and manage, and their small size makes them relatively fast for processing and transmission. The csv module provides various functions and classes which allow you to read and write easily. You can look at the official Python documentation and find some more interesting tips and modules. CSV is the best way for saving, viewing, and sending data. Actually, it isn’t so hard to learn as it seems at the beginning. But with a little practice, you’ll master it. Pandas is a great alternative to read CSV files. Also, there are other ways to parse text files with libraries like ANTLR, PLY, and PlyPlus. They can all handle heavy-duty parsing, and if simple String manipulation doesn’t work, there are regular expressions which you can use. How do I read a specific cell in a CSV file in Python?Using reader. Step 1: In order to read rows in Python, First, we need to load the CSV file in one object. So to load the csv file into an object use open() method.. Step 2: Create a reader object by passing the above-created file object to the reader function.. Step 3: Use for loop on reader object to get each row.. What is the syntax for reading a Comma Separated Value CSV file?M = csvread( filename ) reads a comma-separated value (CSV) formatted file into array M . The file must contain only numeric values. M = csvread( filename , R1 , C1 ) reads data from the file starting at row offset R1 and column offset C1 .
How do I display data in a CSV file?Show activity on this post.. Go to Data -> From Text/CSV.. Choose your CSV file from File Explorer.. Select Transform Data.. Select all cells with Ctrl-A.. Click Use First Row as Headers.. Click Datatype: Any and select Text and click Replace current , if prompted.. Click Close and Load.. How do I read a CSV file row by row in Python using pandas?15 ways to read CSV file with pandas. Example 1 : Read CSV file with header row.. Example 2 : Read CSV file with header in second row.. Example 3 : Skip rows but keep header.. Example 4 : Read CSV file without header row.. Example 5 : Specify missing values.. Example 6 : Set Index Column.. Example 7 : Read CSV File from External URL.. |