I am trying to learn how to submit a Pull-Request to an open-source project. So I chose the issue #23455 from pandas-dev. It is a simple documentation error. However I realized that I have no idea what the nrows actually does in from_records.
I tried
sales = [('Jones LLC', 150, 200, 50),
('Alpha Co', 200, 210, 90),
('Blue Inc', 140, 215, 95)]
labels = ['account', 'Jan', 'Feb', 'Mar']
df = pd.DataFrame.from_records(sales, columns=labels)
which yields
account Jan Feb Mar
0 Jones LLC 150 200 50
1 Alpha Co 200 210 90
2 Blue Inc 140 215 95
as the output. However to my understanding, if I do the following:
df = pd.DataFrame.from_records(sales, columns=labels,nrows=1)
I should only have one row in the df. Instead my output remains the same as the above df.
Can someone help me with this? Thank-you.
nrows is a parameter used to select the first n elements of a record. If you see the code it currently only works on an iterator. There might be some reason why only on an iterator which I currently dont know.
An example to show the use case of nrows is to convert the sales data to an iterator. i.e
sales = iter([('Jones LLC', 150, 200, 50),('Alpha Co', 200, 210, 90), ('Blue Inc', 140, 215, 95)])
df = pd.DataFrame.from_records(sales,nrows=2)
0 1 2 3
0 Jones LLC 150 200 50
1 Alpha Co 200 210 90
sales = iter([('Jones LLC', 150, 200, 50),('Alpha Co', 200, 210, 90), ('Blue Inc', 140, 215, 95)])
df = pd.DataFrame.from_records(sales,nrows=3)
0 1 2 3
0 Jones LLC 150 200 50
1 Alpha Co 200 210 90
2 Blue Inc 140 215 95