Python import csv to list
PythonCsvPython Problem Overview
I have a CSV file with about 2000 records.
Each record has a string, and a category to it:
This is the first line,Line1
This is the second line,Line2
This is the third line,Line3
I need to read this file into a list that looks like this:
data = [('This is the first line', 'Line1'),
('This is the second line', 'Line2'),
('This is the third line', 'Line3')]
How can import this CSV to the list I need using Python?
Python Solutions
Solution 1 - Python
Using the csv module:
import csv
with open('file.csv', newline='') as f:
reader = csv.reader(f)
data = list(reader)
print(data)
Output:
[['This is the first line', 'Line1'], ['This is the second line', 'Line2'], ['This is the third line', 'Line3']]
If you need tuples:
import csv
with open('file.csv', newline='') as f:
reader = csv.reader(f)
data = [tuple(row) for row in reader]
print(data)
Output:
[('This is the first line', 'Line1'), ('This is the second line', 'Line2'), ('This is the third line', 'Line3')]
Old Python 2 answer, also using the csv module:
import csv
with open('file.csv', 'rb') as f:
reader = csv.reader(f)
your_list = list(reader)
print your_list
# [['This is the first line', 'Line1'],
# ['This is the second line', 'Line2'],
# ['This is the third line', 'Line3']]
Solution 2 - Python
Updated for Python 3:
import csv
with open('file.csv', newline='') as f:
reader = csv.reader(f)
your_list = list(reader)
print(your_list)
Output:
[['This is the first line', 'Line1'], ['This is the second line', 'Line2'], ['This is the third line', 'Line3']]
Solution 3 - Python
Pandas is pretty good at dealing with data. Here is one example how to use it:
import pandas as pd
# Read the CSV into a pandas data frame (df)
# With a df you can do many things
# most important: visualize data with Seaborn
df = pd.read_csv('filename.csv', delimiter=',')
# Or export it in many ways, e.g. a list of tuples
tuples = [tuple(x) for x in df.values]
# or export it as a list of dicts
dicts = df.to_dict().values()
One big advantage is that pandas deals automatically with header rows.
If you haven't heard of Seaborn, I recommend having a look at it.
See also: How do I read and write CSV files with Python?
Pandas #2
import pandas as pd
# Get data - reading the CSV file
import mpu.pd
df = mpu.pd.example_df()
# Convert
dicts = df.to_dict('records')
The content of df is:
country population population_time EUR
0 Germany 82521653.0 2016-12-01 True
1 France 66991000.0 2017-01-01 True
2 Indonesia 255461700.0 2017-01-01 False
3 Ireland 4761865.0 NaT True
4 Spain 46549045.0 2017-06-01 True
5 Vatican NaN NaT True
The content of dicts is
[{'country': 'Germany', 'population': 82521653.0, 'population_time': Timestamp('2016-12-01 00:00:00'), 'EUR': True},
{'country': 'France', 'population': 66991000.0, 'population_time': Timestamp('2017-01-01 00:00:00'), 'EUR': True},
{'country': 'Indonesia', 'population': 255461700.0, 'population_time': Timestamp('2017-01-01 00:00:00'), 'EUR': False},
{'country': 'Ireland', 'population': 4761865.0, 'population_time': NaT, 'EUR': True},
{'country': 'Spain', 'population': 46549045.0, 'population_time': Timestamp('2017-06-01 00:00:00'), 'EUR': True},
{'country': 'Vatican', 'population': nan, 'population_time': NaT, 'EUR': True}]
Pandas #3
import pandas as pd
# Get data - reading the CSV file
import mpu.pd
df = mpu.pd.example_df()
# Convert
lists = [[row[col] for col in df.columns] for row in df.to_dict('records')]
The content of lists is:
[['Germany', 82521653.0, Timestamp('2016-12-01 00:00:00'), True],
['France', 66991000.0, Timestamp('2017-01-01 00:00:00'), True],
['Indonesia', 255461700.0, Timestamp('2017-01-01 00:00:00'), False],
['Ireland', 4761865.0, NaT, True],
['Spain', 46549045.0, Timestamp('2017-06-01 00:00:00'), True],
['Vatican', nan, NaT, True]]
Solution 4 - Python
Update for Python3:
import csv
from pprint import pprint
with open('text.csv', newline='') as file:
reader = csv.reader(file)
res = list(map(tuple, reader))
pprint(res)
Output:
[('This is the first line', ' Line1'), ('This is the second line', ' Line2'), ('This is the third line', ' Line3')]
If csvfile is a file object, it should be opened with newline=''.
csv module
Solution 5 - Python
If you are sure there are no commas in your input, other than to separate the category, you can read the file line by line and split on ,, then push the result to List
That said, it looks like you are looking at a CSV file, so you might consider using the modules for it
Solution 6 - Python
result = []
for line in text.splitlines():
result.append(tuple(line.split(",")))
Solution 7 - Python
You can use the list() function to convert csv reader object to list
import csv
with open('input.csv', newline='') as csv_file:
reader = csv.reader(csv_file, delimiter=',')
rows = list(reader)
print(rows)
Solution 8 - Python
A simple loop would suffice:
lines = []
with open('test.txt', 'r') as f:
for line in f.readlines():
l,name = line.strip().split(',')
lines.append((l,name))
print lines
Solution 9 - Python
As said already in the comments you can use the csv library in python. csv means comma separated values which seems exactly your case: a label and a value separated by a comma.
Being a category and value type I would rather use a dictionary type instead of a list of tuples.
Anyway in the code below I show both ways: d is the dictionary and l is the list of tuples.
import csv
file_name = "test.txt"
try:
csvfile = open(file_name, 'rt')
except:
print("File not found")
csvReader = csv.reader(csvfile, delimiter=",")
d = dict()
l = list()
for row in csvReader:
d[row[1]] = row[0]
l.append((row[0], row[1]))
print(d)
print(l)
Solution 10 - Python
Unfortunately I find none of the existing answers particularly satisfying.
Here is a straightforward and complete Python 3 solution, using the csv module.
import csv
with open('../resources/temp_in.csv', newline='') as f:
reader = csv.reader(f, skipinitialspace=True)
rows = list(reader)
print(rows)
Notice the skipinitialspace=True argument. This is necessary since, unfortunately, OP's CSV contains whitespace after each comma.
Output:
[['This is the first line', 'Line1'], ['This is the second line', 'Line2'], ['This is the third line', 'Line3']]
Solution 11 - Python
Extending your requirements a bit and assuming you do not care about the order of lines and want to get them grouped under categories, the following solution may work for you:
>>> fname = "lines.txt"
>>> from collections import defaultdict
>>> dct = defaultdict(list)
>>> with open(fname) as f:
... for line in f:
... text, cat = line.rstrip("\n").split(",", 1)
... dct[cat].append(text)
...
>>> dct
defaultdict(<type 'list'>, {' CatA': ['This is the first line', 'This is the another line'], ' CatC': ['This is the third line'], ' CatB': ['This is the second line', 'This is the last line']})
This way you get all relevant lines available in the dictionary under key being the category.
Solution 12 - Python
Here is the easiest way in Python 3.x to import a CSV to a multidimensional array, and its only 4 lines of code without importing anything!
#pull a CSV into a multidimensional array in 4 lines!
L=[] #Create an empty list for the main array
for line in open('log.txt'): #Open the file and read all the lines
x=line.rstrip() #Strip the \n from each line
L.append(x.split(',')) #Split each line into a list and add it to the
#Multidimensional array
print(L)
Solution 13 - Python
Next is a piece of code which uses csv module but extracts file.csv contents to a list of dicts using the first line which is a header of csv table
import csv
def csv2dicts(filename):
with open(filename, 'rb') as f:
reader = csv.reader(f)
lines = list(reader)
if len(lines) < 2: return None
names = lines[0]
if len(names) < 1: return None
dicts = []
for values in lines[1:]:
if len(values) != len(names): return None
d = {}
for i,_ in enumerate(names):
d[names[i]] = values[i]
dicts.append(d)
return dicts
return None
if __name__ == '__main__':
your_list = csv2dicts('file.csv')
print your_list