How to read all rows of a csv file using pandas in python?

Question

I am using the pandas module for reading the data from a .csv file.

I can write out the following code to extract the data belonging to an individual column as follows:

import pandas as pd

df = pd.read_csv('somefile.tsv', sep='\t', header=0)
some_column = df.column_name
print some_column # Gives the values of all entries in the column

However, the file that I am trying to read now has more than 5000 columns and writing out the statement

some_column = df.column_name

is now not feasible. How can I get all the column values so that I can access them using indexing?

e.g to extract the value present at the 100th row and the 50th column, I should be able to write something like this:

df([100][50])

jezrael · Accepted Answer · 2016-11-25 09:33:03Z

5

Use DataFrame.iloc or DataFrame.iat, but python counts from 0, so need 99 and 49 for select 100. row and 50. column:

df = df.iloc[99,49]

Sample - select 3. row and 4. column:

df = pd.DataFrame({'A':[1,2,3],
                   'B':[4,5,6],
                   'C':[7,8,9],
                   'D':[1,3,10],
                   'E':[5,3,6],
                   'F':[7,4,3]})

print (df)
   A  B  C   D  E  F
0  1  4  7   1  5  7
1  2  5  8   3  3  4
2  3  6  9  10  6  3

print (df.iloc[2,3])
10

print (df.iat[2,3])
10

Combination for selecting by column name and position of row is possible by Series.iloc or Series.iat:

print (df['D'].iloc[2])
10

print (df['D'].iat[2])
10

edited Nov 25, 2016 at 9:33

answered Nov 25, 2016 at 9:22

jezrael

868k103 gold badges1.4k silver badges1.3k bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Spider Man Over a year ago

Thanks. Works as desired

Spider Man Over a year ago

Moreover, how do I find out the total number of columns from df variable?

jezrael Over a year ago

do you think len(df.columns) ?

Spider Man Over a year ago

Thanks a lot @jezrael. Works as expected

jezrael Over a year ago

Glad can help you!

|

RichSmith · Accepted Answer · 2016-11-25 09:23:22Z

1

Pandas has indexing for dataframes, so you can use

df.iloc[[index]]["column header"]

the index is in a list as you can pass multiple indexes at one in this way.

answered Nov 25, 2016 at 9:23

RichSmith

9405 silver badges11 bronze badges

Collectives™ on Stack Overflow

How to read all rows of a csv file using pandas in python?

2 Answers 2

7 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

7 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related