Python | Read csv using pandas.read_csv()
Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric python packages. Pandas is one of those packages and makes importing and analyzing data much easier.
Import Pandas:
import pandas as pd
Code #1 : read_csv is an important pandas function to read csv files and do operations on it.
PYTHON3
# Import pandas import pandas as pd # reading csv file pd.read_csv( "filename.csv" ) |
Opening a CSV file through this is easy. But there are many others thing one can do through this function only to change the returned object completely. For instance, one can read a csv file not only locally, but from a URL through read_csv or one can choose what columns needed to export so that we don’t have to edit the array later.
Here is the list of parameters it takes with their Default values.
pd.read_csv(filepath_or_buffer, sep=’, ‘, delimiter=None, header=’infer’, names=None, index_col=None, usecols=None, squeeze=False, prefix=None, mangle_dupe_cols=True, dtype=None, engine=None, converters=None, true_values=None, false_values=None, skipinitialspace=False, skiprows=None, nrows=None, na_values=None, keep_default_na=True, na_filter=True, verbose=False, skip_blank_lines=True, parse_dates=False, infer_datetime_format=False, keep_date_col=False, date_parser=None, dayfirst=False, iterator=False, chunksize=None, compression=’infer’, thousands=None, decimal=b’.’, lineterminator=None, quotechar='”‘, quoting=0, escapechar=None, comment=None, encoding=None, dialect=None, tupleize_cols=None, error_bad_lines=True, warn_bad_lines=True, skipfooter=0, doublequote=True, delim_whitespace=False, low_memory=True, memory_map=False, float_precision=None)
Not all of them are much important but remembering these actually save time of performing same functions on own. One can see parameters of any function by pressing shift + tab in jupyter notebook. Useful ones are given below with their usage : Makes passed column as index instead of 0, 1, 2, 3…r Makes passed row/s[int/int list] as header
Parameter Use filepath_or_buffer URL or Dir location of file sep Stands for separator, default is ‘, ‘ as in csv(comma separated values) index_col
header
use_cols Only uses the passed col[string list] to make data frame squeeze If true and only one column is passed, returns pandas series skiprows Skips passed rows in new data frame
Refer the link to data set used from here.
Code #2 :
PYTHON3
# importing Pandas library import pandas as pd pd.read_csv(filepath_or_buffer = "pokemon.csv" ) # makes the passed rows header pd.read_csv( "pokemon.csv" , header = [ 1 , 2 ]) # make the passed column as index instead of 0, 1, 2, 3.... pd.read_csv( "pokemon.csv" , index_col = 'Type' ) # uses passed cols only for data frame pd.read_csv( "pokemon.csv" , usecols = [ "Type" ]) # returns pandas series if there is only one column pd.read_csv( "pokemon.csv" , usecols = [ "Type" ], squeeze = True ) # skips the passed rows in new series pd.read_csv( "pokemon.csv" , skiprows = [ 1 , 2 , 3 , 4 ]) |