CODEWITHSUNDEEP
pythonpandascsv
John Constantine
John Constantine

Reputation: 1092

Reading a part of csv file

I have a really large csv file about 10GB. When ever I try to read in into iPython notebook using

data = pd.read_csv("data.csv")

my laptop gets stuck. Is it possible to just read like 10,000 rows or 500 MB of a csv file.

Upvotes: 5

Views: 17527

Answers (2)

miradulo
miradulo

Reputation: 29690

It is possible. You can create an iterator yielding chunks of your csv of a certain size at a time as a DataFrame by passing iterator=True with your desired chunksize to read_csv. 

df_iter = pd.read_csv('data.csv', chunksize=10000, iterator=True)

for iter_num, chunk in enumerate(df_iter, 1):
    print(f'Processing iteration {iter_num}')
    # do things with chunk

Or more briefly

for chunk in pd.read_csv('data.csv', chunksize=10000):
    # do things with chunk

Alternatively if there was just a specific part of the csv you wanted to read, you could use the skiprows and nrows options to start at a particular line and subsequently read n rows, as the naming suggests.

Upvotes: 14

user3212593
user3212593

Reputation: 496

Likely a memory issue. On read_csv you can set chunksize (where you can specify number of rows).

Alternatively, if you don't need all the columns, you can change usecols on read_csv to import only the columns you need.

Upvotes: 0

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