Get list from pandas dataframe column or row?
I have a dataframe df
imported from an Excel document like this:
cluster load_date budget actual fixed_price
A 1/1/2014 1000 4000 Y
A 2/1/2014 12000 10000 Y
A 3/1/2014 36000 2000 Y
B 4/1/2014 15000 10000 N
B 4/1/2014 12000 11500 N
B 4/1/2014 90000 11000 N
C 7/1/2014 22000 18000 N
C 8/1/2014 30000 28960 N
C 9/1/2014 53000 51200 N
I want to be able to return the contents of column 1 df['cluster']
as a list, so I can run a for-loop over it, and create an Excel worksheet for every cluster.
Is it also possible to return the contents of a whole column or row to a list? e.g.
list = [], list[column1] or list[df.ix(row1)]
Solution 1:
Pandas DataFrame columns are Pandas Series when you pull them out, which you can then call x.tolist()
on to turn them into a Python list. Alternatively you cast it with list(x)
.
import pandas as pd
data_dict = {'one': pd.Series([1, 2, 3], index=['a', 'b', 'c']),
'two': pd.Series([1, 2, 3, 4], index=['a', 'b', 'c', 'd'])}
df = pd.DataFrame(data_dict)
print(f"DataFrame:\n{df}\n")
print(f"column types:\n{df.dtypes}")
col_one_list = df['one'].tolist()
col_one_arr = df['one'].to_numpy()
print(f"\ncol_one_list:\n{col_one_list}\ntype:{type(col_one_list)}")
print(f"\ncol_one_arr:\n{col_one_arr}\ntype:{type(col_one_arr)}")
Output:
DataFrame:
one two
a 1.0 1
b 2.0 2
c 3.0 3
d NaN 4
column types:
one float64
two int64
dtype: object
col_one_list:
[1.0, 2.0, 3.0, nan]
type:<class 'list'>
col_one_arr:
[ 1. 2. 3. nan]
type:<class 'numpy.ndarray'>
Solution 2:
This returns a numpy array:
arr = df["cluster"].to_numpy()
This returns a numpy array of unique values:
unique_arr = df["cluster"].unique()
You can also use numpy to get the unique values, although there are differences between the two methods:
arr = df["cluster"].to_numpy()
unique_arr = np.unique(arr)
Solution 3:
Example conversion:
Numpy Array -> Panda Data Frame -> List from one Panda Column
Numpy Array
data = np.array([[10,20,30], [20,30,60], [30,60,90]])
Convert numpy array into Panda data frame
dataPd = pd.DataFrame(data = data)
print(dataPd)
0 1 2
0 10 20 30
1 20 30 60
2 30 60 90
Convert one Panda column to list
pdToList = list(dataPd['2'])