I want to create a dataframe in Python with 24 columns (indicating 24 hours), which looks like this:
column name 0 1 2 3 ... 24
row 1 0 0 0 0 0
row 2 0 0 0 0 0
row 3 0 0 0 0 0
I would like to know how to initialize it? and in the future, I may add row 4, with all "0", how to do that? Thanks,
There's a trick here: when DataFrame (or Series) constructor is passed a scalar as the first argument this value is propogated:
In [11]: pd.DataFrame(0, index=np.arange(1, 4), columns=np.arange(24))
Out[11]:
0 1 2 3 4 5 6 7 8 9 ... 14 15 16 17 18 19 20 21 22 23
1 0 0 0 0 0 0 0 0 0 0 ... 0 0 0 0 0 0 0 0 0 0
2 0 0 0 0 0 0 0 0 0 0 ... 0 0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 0 0 0 0 ... 0 0 0 0 0 0 0 0 0 0
[3 rows x 24 columns]
Note: np.arange is numpy's answer to python's range.
You can create an empty numpy array, convert it to a dataframe, and then add the header names.
import numpy
a = numpy.zeros(shape=(3,24))
df = pd.DataFrame(a,columns=['col1','col2', etc..])
to set row names use
df.set_index(['row1', 'row2', etc..])
if you must.
