Menu
I've got a dataframe with a multi index of Year and Month like the following
| |Value
Year |Month|
| 1 | 3
1992 | 2 | 5
| 3 | 8
| ... | ...
1993 | 1 | 2
| ... | ...
I'm trying to select the maximum Value for each year and put that in a DF like this:
| Max
Year |
1992 | 5
1993 | 2
| ...
There's not much info on multi-indexes, should I simply do a group by and apply or something similar to make it more simple?
637
iloc selects rows based on an integer index. So, if you want to select the 5th row in a DataFrame, you would use df. iloc[[4]] since the first row is at index 0, the second row is at index 1, and so on.
You can slice a MultiIndex by providing multiple indexers. You can provide any of the selectors as if you are indexing by label, see Selection by Label, including slices, lists of labels, labels, and boolean indexers. You can use slice(None) to select all the contents of that level.
Pandas DataFrame idxmax() Method The idxmax() method returns a Series with the index of the maximum value for each column. By specifying the column axis ( axis='columns' ), the idxmax() method returns a Series with the index of the maximum value for each row.
A multi-index dataframe has multi-level, or hierarchical indexing. We can easily convert the multi-level index into the column by the reset_index() method. DataFrame. reset_index() is used to reset the index to default and make the index a column of the dataframe.
Exactly right:
df.groupby(level=0).apply(max)
In my sample DataFrame:
0
Caps Lower
A a 0 0.246490
1 -1.265711
2 -0.477415
3 -0.355812
4 -0.724521
b 0 -0.409198
1 -0.062552
2 -0.731789
3 1.131616
4 0.085248
B a 0 0.193948
1 2.010710
2 0.289300
3 0.305373
4 1.376965
b 0 0.210522
1 1.431279
2 -0.247171
3 0.899074
4 0.639926
Result:
0
Caps
A 1.131616
B 2.010710
This is how I created the DataFrame, by the way:
df = pd.DataFrame(np.random.randn(5,4), columns = l)
df.columns = pd.MultiIndex.from_tuples(df.columns, names=['Caps','Lower'])
df = pd.DataFrame(df.unstack())
Simplier solution is max only:
#bernie's sample data
df = df.max(level=0)
print (df)
0
Caps
A 1.131616
B 2.010710
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
