I have a DF:
Col1 Col2 Label
0 0 5345
1 0 7574
2 0 3445
0 1 2126
1 1 4653
2 1 9566
So I'm trying to groupby on Col1 and Col2 to get index value based on Label column like this:
df_gb = df.groupby(['Col1','Col2'])['Label'].agg(['sum', 'count'])
df_gb['sum_count'] = df_gb['sum'] / df_gb['count']
sum_count_total = df_gb['sum_count'].sum()
index = df_gb['sum_count'] / 10
Col2 Col1
0 0 2.996036
1 3.030063
2 3.038579
1 0 2.925314
1 2.951295
2 2.956083
2 0 2.875549
1 2.899254
2 2.905063
Everything so far is as I expected. But now I would like to assign this 'index' groupby df to my original 'df' based on those two groupby columns. If it was only one column it's working with map() function but not if I would like to assign index values based on two columns order.
df_index = df.copy()
df_index['index'] = df.groupby([]).apply(index)
TypeError: 'Series' objects are mutable, thus they cannot be hashed
Tried with agg() and transform() but without success. Any ideas how to proceed?
Thanks in advance.
Hristo.
I believe you need join:
a = df.join(index.rename('new'), on=['Col1','Col2'])
print (a)
Col1 Col2 Label new
0 0 0 5345 534.5
1 1 0 7574 757.4
2 2 0 3445 344.5
3 0 1 2126 212.6
4 1 1 4653 465.3
5 2 1 9566 956.6
Or GroupBy.transform:
df['new']=df.groupby(['Col1','Col2'])['Label'].transform(lambda x: x.sum() / x.count()) / 10
print (df)
Col1 Col2 Label new
0 0 0 5345 534.5
1 1 0 7574 757.4
2 2 0 3445 344.5
3 0 1 2126 212.6
4 1 1 4653 465.3
5 2 1 9566 956.6
And if no NaNs in Label column use solution from Zero suggestion, thank you:
df.groupby(['Col1','Col2'])['Label'].transform('mean') / 10
If need count only non NaNs values by count use solution with transform.
Related
I have data that looks like this:
CHROM POS REF ALT ... is_sever_int is_sever_str is_sever_f encoding_str
0 chr1 14907 A G ... 1 1 one one
1 chr1 14930 A G ... 1 1 one one
These are the columns that I'm interested to perform calculations on (example) :
is_severe snp _id encoding
1 1 one
1 1 two
0 1 one
1 2 two
0 2 two
0 2 one
what I want to do is to count for each snp_id and severe_id how many ones and twos are in the encoding column :
snp_id is_svere encoding_one encoding_two
1 1 1 1
1 0 1 0
2 1 0 1
2 0 1 1
I tried this :
df.groupby(["snp_id","is_sever_f","encoding_str"])["encoding_str"].count()
but it gave the error :
incompatible index of inserted column with frame index
then i tried this:
df["count"]=df.groupby(["snp_id","is_sever_f","encoding_str"],as_index=False)["encoding_str"].count()
and it returned:
Expected a 1D array, got an array with shape (2532831, 3)
how can i fix this? thank you:)
Let's try groupby with whole columns and get size of each group then unstack the encoding index.
out = (df.groupby(['is_severe', 'snp_id', 'encoding']).size()
.unstack(fill_value=0)
.add_prefix('encoding_')
.reset_index())
print(out)
encoding is_severe snp_id encoding_one encoding_two
0 0 1 1 0
1 0 2 1 1
2 1 1 1 1
3 1 2 0 1
Try as follows:
Use pd.get_dummies to convert categorical data in column encoding into indicator variables.
Chain df.groupby and get sum to turn double rows per group into one row (i.e. [0,1] and [1,0] will become [1,1] where df.snp_id == 2 and df.is_severe == 0).
res = pd.get_dummies(data=df, columns=['encoding'])\
.groupby(['snp_id','is_severe'], as_index=False, sort=False).sum()
print(res)
snp_id is_severe encoding_one encoding_two
0 1 1 1 1
1 1 0 1 0
2 2 1 0 1
3 2 0 1 1
If your actual df has more columns, limit the assigment to the data parameter inside get_dummies. I.e. use:
res = pd.get_dummies(data=df[['is_severe', 'snp_id', 'encoding']],
columns=['encoding']).groupby(['snp_id','is_severe'],
as_index=False, sort=False)\
.sum()
I have a pandas data frame and I wanna make a new columns with 0 and 1:
if col1 is zero and col2 is positive set new column to 1.
if 'col1is zero andcol2is negative set new column to 0. ifcol1is 1 andcol2 is positive set new column to 0. if 'col1 is 1 and col2 is negative set new column to 1.
col1 col2
0 2
0 -4
1 -2
1 5
1 9
new_colum
1
0
1
0
0
You can determine if col2 is positive and get the absolute difference with col1 (booleans behave like 0/1):
df['new_column'] = df['col1'].sub(df['col2'].gt(0)).abs()
Or, compare the two outputs, you want them to be different:
df['new_column'] = df['col1'].ne(df['col2'].gt(0)).astype(int)
output:
col1 col2 new_column
0 0 2 1
1 0 -4 0
2 1 -2 1
3 1 5 0
4 1 9 0
I have a pandas dataframe with some numeric and some categoric columns. I want to create a new column for each value of every categorical column and give that column a value of 1 in every row where that value is true and 0 in every row where that value is false. So the df is something like this -
col1 col2 col3
A P 1
B P 3
A Q 7
expected result is something like this:
col1 col2 col3 A B P Q
A P 1 1 0 1 0
B P 3 0 1 1 0
A Q 7 1 0 0 1
Is this possible? can someone please help me?
Use df.select_dtypes, pd.get_dummies with pd.concat:
# First select all columns which have object dtypes
In [826]: categorical_cols = df.select_dtypes('object').columns
# Create one-hot encoding for the above cols and concat with df
In [817]: out = pd.concat([df, pd.get_dummies(df[categorical_cols])], 1)
In [818]: out
Out[818]:
col1 col2 col3 col1_A col1_B col2_P col2_Q
0 A P 1 1 0 1 0
1 B P 3 0 1 1 0
2 A Q 7 1 0 0 1
I have a .dat file containing the following data:
0001100000101010100
110101000001111
101100011001110111
0111111010100
1010111111100011
Need to count number of zeros and ones in each row
I have tried with Pandas.
Step-1: Read the data file
Step-2: Given a column name
Step-3: Tried to split the values into multiple columns. But could
not succeed
df1=pd.read_csv('data.dat',header=None) df1.head()
0 1100000101010100
1 110101000001111
2 101100011001110111
3 111111010100
4 1010111111100011
df1.columns=['kirti']
df1.head()
Kirti
_______________________
0 1100000101010100
1 110101000001111
2 101100011001110111
3 111111010100
4 1010111111100011
I need to split the data frame into multiple columns depending upon the 0s and 1s in each row.
the maximum number of columns will be equal to max no of zeros and ones in any of the rows in the data frame.
First create one column DataFrame by parameters names and dtype=str for convert column to strings:
import pandas as pd
temp="""0001100000101010100
110101000001111
101100011001110111
0111111010100
1010111111100011"""
#after testing replace 'pd.compat.StringIO(temp)' to 'filename'
df = pd.read_csv(StringIO(temp), header=None, names=['kirti'], dtype=str)
print (df)
kirti
0 0001100000101010100
1 110101000001111
2 101100011001110111
3 0111111010100
4 1010111111100011
And then create new DataFrame by convert values to lists:
df = pd.DataFrame([list(x) for x in df['kirti']])
print (df)
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18
0 0 0 0 1 1 0 0 0 0 0 1 0 1 0 1 0 1 0 0
1 1 1 0 1 0 1 0 0 0 0 0 1 1 1 1 None None None None
2 1 0 1 1 0 0 0 1 1 0 0 1 1 1 0 1 1 1 None
3 0 1 1 1 1 1 1 0 1 0 1 0 0 None None None None None None
4 1 0 1 0 1 1 1 1 1 1 1 0 0 0 1 1 None None None
If your data is in a list of strings, then use the count method:
>> data = ["0001100000101010100", "110101000001111", "101100011001110111", "0111111010100", "1010111111100011"]
>> for i in data:
print(i.count("0"))
13
7
7
5
5
If your data is in a .dat file with whitespace sepparation as you discribed, then I would recommend loading your data as follows:
data = pd.read_csv("data.dat", lineterminator=" ",dtype="str", header=None, names=["Kirti"])
Kirti
0 0001100000101010100
1 110101000001111
2 101100011001110111
3 0111111010100
4 1010111111100011
The lineterminator argument ensures that every entry is in a new row. The dtype argument ensures that it's read as string. Otherwise you will loose leading zeros.
If your data is in a DataFrame, you can use the count method (inspired from here):
>> data["Kirti"].str.count("0")
0 13
1 7
2 7
3 5
4 5
Name: Kirti, dtype: int64
I'm using groupby on a pandas dataframe to drop all rows that don't have the minimum of a specific column. Something like this:
df1 = df.groupby("item", as_index=False)["diff"].min()
However, if I have more than those two columns, the other columns (e.g. otherstuff in my example) get dropped. Can I keep those columns using groupby, or am I going to have to find a different way to drop the rows?
My data looks like:
item diff otherstuff
0 1 2 1
1 1 1 2
2 1 3 7
3 2 -1 0
4 2 1 3
5 2 4 9
6 2 -6 2
7 3 0 0
8 3 2 9
and should end up like:
item diff otherstuff
0 1 1 2
1 2 -6 2
2 3 0 0
but what I'm getting is:
item diff
0 1 1
1 2 -6
2 3 0
I've been looking through the documentation and can't find anything. I tried:
df1 = df.groupby(["item", "otherstuff"], as_index=false)["diff"].min()
df1 = df.groupby("item", as_index=false)["diff"].min()["otherstuff"]
df1 = df.groupby("item", as_index=false)["otherstuff", "diff"].min()
But none of those work (I realized with the last one that the syntax is meant for aggregating after a group is created).
Method #1: use idxmin() to get the indices of the elements of minimum diff, and then select those:
>>> df.loc[df.groupby("item")["diff"].idxmin()]
item diff otherstuff
1 1 1 2
6 2 -6 2
7 3 0 0
[3 rows x 3 columns]
Method #2: sort by diff, and then take the first element in each item group:
>>> df.sort_values("diff").groupby("item", as_index=False).first()
item diff otherstuff
0 1 1 2
1 2 -6 2
2 3 0 0
[3 rows x 3 columns]
Note that the resulting indices are different even though the row content is the same.
You can use DataFrame.sort_values with DataFrame.drop_duplicates:
df = df.sort_values(by='diff').drop_duplicates(subset='item')
print (df)
item diff otherstuff
6 2 -6 2
7 3 0 0
1 1 1 2
If possible multiple minimal values per groups and want all min rows use boolean indexing with transform for minimal values per groups:
print (df)
item diff otherstuff
0 1 2 1
1 1 1 2 <-multiple min
2 1 1 7 <-multiple min
3 2 -1 0
4 2 1 3
5 2 4 9
6 2 -6 2
7 3 0 0
8 3 2 9
print (df.groupby("item")["diff"].transform('min'))
0 1
1 1
2 1
3 -6
4 -6
5 -6
6 -6
7 0
8 0
Name: diff, dtype: int64
df = df[df.groupby("item")["diff"].transform('min') == df['diff']]
print (df)
item diff otherstuff
1 1 1 2
2 1 1 7
6 2 -6 2
7 3 0 0
The above answer worked great if there is / you want one min. In my case there could be multiple mins and I wanted all rows equal to min which .idxmin() doesn't give you. This worked
def filter_group(dfg, col):
return dfg[dfg[col] == dfg[col].min()]
df = pd.DataFrame({'g': ['a'] * 6 + ['b'] * 6, 'v1': (list(range(3)) + list(range(3))) * 2, 'v2': range(12)})
df.groupby('g',group_keys=False).apply(lambda x: filter_group(x,'v1'))
As an aside, .filter() is also relevant to this question but didn't work for me.
I tried everyone's method and I couldn't get it to work properly. Instead I did the process step-by-step and ended up with the correct result.
df.sort_values(by='item', inplace=True, ignore_index=True)
df.drop_duplicates(subset='diff', inplace=True, ignore_index=True)
df.sort_values(by=['diff'], inplace=True, ignore_index=True)
For a little more explanation:
Sort items by the minimum value you want
Drop the duplicates of the column you want to sort with
Resort the data because the data is still sorted by the minimum values
If you know that all of your "items" have more than one record you can sort, then use duplicated:
df.sort_values(by='diff').duplicated(subset='item', keep='first')