from pandas import *
import StringIO
df = read_csv(StringIO.StringIO('''id months state
1 1 C
1 2 3
1 3 6
1 4 9
2 1 C
2 2 C
2 3 3
2 4 6
2 5 9
2 6 9
2 7 9
2 8 C
'''), delimiter= '\t')
I want to create a column show the cumulative state of column state, by id.
id months state result
1 1 C C
1 2 3 C3
1 3 6 C36
1 4 9 C369
2 1 C C
2 2 C CC
2 3 3 CC3
2 4 6 CC36
2 5 9 CC69
2 6 9 CC699
2 7 9 CC6999
2 8 C CC6999C
Basically the cum concatenation of string columns. What is the best way to do it?
So long as the dtype is str then you can do the following:
In [17]:
df['result']=df.groupby('id')['state'].apply(lambda x: x.cumsum())
df
Out[17]:
id months state result
0 1 1 C C
1 1 2 3 C3
2 1 3 6 C36
3 1 4 9 C369
4 2 1 C C
5 2 2 C CC
6 2 3 3 CC3
7 2 4 6 CC36
8 2 5 9 CC369
9 2 6 9 CC3699
10 2 7 9 CC36999
11 2 8 C CC36999C
Essentially we groupby on 'id' column and then apply a lambda with a transform to return the cumsum. This will perform a cumulative concatenation of the string values and return a Series with it's index aligned to the original df so you can add it as a column
Related
Starting Dataframe:
A B
0 1 1
1 1 2
2 2 3
3 3 4
4 3 5
5 1 6
6 1 7
7 1 8
8 2 9
Desired result - eg. Remove rows where column A has values that match the row above or below:
A B
0 1 1
2 2 3
3 3 4
5 1 6
8 2 9
You can use boolean indexing, the following condition will return true if value of A is NOT equal to value of A's next row
new_df = df[df['A'].ne(df['A'].shift())]
A B
0 1 1
2 2 3
3 3 4
5 1 6
8 2 9
I have a df like this:
Index Parameters A B C D E
1 Apple 1 2 3 4 5
2 Banana 2 4 5 3 5
3 Potato 3 5 3 2 1
4 Tomato 1 1 1 1 1
5 Pear 4 5 5 4 3
I want to add all the rows which has Parameter values as "Apple" , "Banana" and "Pear".
Output:
Index Parameters A B C D E
1 Apple 1 2 3 4 5
2 Banana 2 4 5 3 5
3 Potato 3 5 3 2 1
4 Tomato 1 1 1 1 1
5 Pear 4 5 5 4 3
6 Total 7 11 13 11 13
My Effort:
df[:,'Total'] = df.sum(axis=1) -- Works but I want specific values only and not all
Tried by the index in my case 1,2 and 5 but in my original df the index can vary from time to time and hence rejected that solution.
Saw various answers on SO but none of them could solve my problem!!
First idea is create index by Parameters column and select rows for sum and last convert index to column:
L = ["Apple" , "Banana" , "Pear"]
df = df.set_index('Parameters')
df.loc['Total'] = df.loc[L].sum()
df = df.reset_index()
print (df)
Parameters A B C D E
0 Apple 1 2 3 4 5
1 Banana 2 4 5 3 5
2 Potato 3 5 3 2 1
3 Tomato 1 1 1 1 1
4 Pear 4 5 5 4 3
5 Total 7 11 13 11 13
Or add new row for filtered rows by membership with Series.isin and overwrite last added value by Total:
last = len(df)
df.loc[last] = df[df['Parameters'].isin(L)].sum()
df.loc[last, 'Parameters'] = 'Total'
print (df)
Parameters A B C D E
Index
1 Apple 1 2 3 4 5
2 Banana 2 4 5 3 5
3 Potato 3 5 3 2 1
4 Tomato 1 1 1 1 1
5 Total 7 11 13 11 13
Another similar solution is filtering all columns without first and add value in one element list:
df.loc[len(df)] = ['Total'] + df.iloc[df['Parameters'].isin(L).values, 1:].sum().tolist()
Id B
1 6
2 13
1 6
2 6
1 6
2 6
1 10
2 6
2 6
2 6
I want a new columns say C where I can get a grouped value of B=6 at Id level
Jan18.loc[Jan18['Enquiry Purpose']==6].groupby(Jan18['Member Reference']).transform('count')
Id B No_of_6
1 6 3
2 13 5
1 6 3
2 6 5
1 6 3
2 6 5
1 10 3
2 6 5
2 6 5
2 6 5
Comapre values by Series.eq for ==, convert to integers and use GroupBy.transform for new column filled by sum per groups:
df['No_of_6'] = df['B'].eq(6).astype(int).groupby(df['Id']).transform('sum')
#alternative
#df['No_of_6'] = df.assign(B= df['B'].eq(6).astype(int)).groupby('Id')['B'].transform('sum')
print (df)
Id B No_of_6
0 1 6 3
1 2 13 5
2 1 6 3
3 2 6 5
4 1 6 3
5 2 6 5
6 1 10 3
7 2 6 5
8 2 6 5
9 2 6 5
Generally create boolean mask by your condition(s) and pass below:
mask = df['B'].eq(6)
#alternative
#mask = (df['B'] == 6)
df['No_of_6'] = mask.astype(int).groupby(df['Id']).transform('sum')
A solution using map. This solution will return NaN on groups of Id have no number of 6
df['No_of_6'] = df.Id.map(df[df.B.eq(6)].groupby('Id').B.count())
Out[113]:
Id B No_of_6
0 1 6 3
1 2 13 5
2 1 6 3
3 2 6 5
4 1 6 3
5 2 6 5
6 1 10 3
7 2 6 5
8 2 6 5
9 2 6 5
I have a dataframe looks like,
A B
1 2
1 3
1 4
2 5
2 6
3 7
3 8
If I df.groupby('A'), how do I turn each group into sub-dataframes, so it will look like, for A=1
A B
1 2
1 3
1 4
for A=2,
A B
2 5
2 6
for A=3,
A B
3 7
3 8
By using get_group
g=df.groupby('A')
g.get_group(1)
Out[367]:
A B
0 1 2
1 1 3
2 1 4
You are close, need convert groupby object to dictionary of DataFrames:
dfs = dict(tuple(df.groupby('A')))
print (dfs[1])
A B
0 1 2
1 1 3
2 1 4
print (dfs[2])
A B
3 2 5
4 2 6
Hi all I have the following dataframe:
A | B | C
1 2 3
2 3 4
3 4 5
4 5 6
And I am trying to only repeat the last two rows of the data so that it looks like this:
A | B | C
1 2 3
2 3 4
3 4 5
3 4 5
4 5 6
4 5 6
I have tried using append, concat and repeat to no avail.
repeated = lambda x:x.repeat(2)
df.append(df[-2:].apply(repeated),ignore_index=True)
This returns the following dataframe, which is incorrect:
A | B | C
1 2 3
2 3 4
3 4 5
4 5 6
3 4 5
3 4 5
4 5 6
4 5 6
You can use numpy.repeat for repeating index and then create df1 by loc, last append to original, but before filter out last 2 rows by iloc:
df1 = df.loc[np.repeat(df.index[-2:].values, 2)]
print (df1)
A B C
2 3 4 5
2 3 4 5
3 4 5 6
3 4 5 6
print (df.iloc[:-2])
A B C
0 1 2 3
1 2 3 4
df = df.iloc[:-2].append(df1,ignore_index=True)
print (df)
A B C
0 1 2 3
1 2 3 4
2 3 4 5
3 3 4 5
4 4 5 6
5 4 5 6
If want use your code add iloc for filtering only last 2 rows:
repeated = lambda x:x.repeat(2)
df = df.iloc[:-2].append(df.iloc[-2:].apply(repeated),ignore_index=True)
print (df)
A B C
0 1 2 3
1 2 3 4
2 3 4 5
3 3 4 5
4 4 5 6
5 4 5 6
Use pd.concat and index slicing with .iloc:
pd.concat([df,df.iloc[-2:]]).sort_values(by='A')
Output:
A B C
0 1 2 3
1 2 3 4
2 3 4 5
2 3 4 5
3 4 5 6
3 4 5 6
I'm partial to manipulating the index into the pattern we are aiming for then asking the dataframe to take the new form.
Option 1
Use pd.DataFrame.reindex
df.reindex(df.index[:-2].append(df.index[-2:].repeat(2)))
A B C
0 1 2 3
1 2 3 4
2 3 4 5
2 3 4 5
3 4 5 6
3 4 5 6
Same thing in multiple lines
i = df.index
idx = i[:-2].append(i[-2:].repeat(2))
df.reindex(idx)
Could also use loc
i = df.index
idx = i[:-2].append(i[-2:].repeat(2))
df.loc[idx]
Option 2
Reconstruct from values. Only do this is all dtypes are the same.
i = np.arange(len(df))
idx = np.append(i[:-2], i[-2:].repeat(2))
pd.DataFrame(df.values[idx], df.index[idx])
0 1 2
0 1 2 3
1 2 3 4
2 3 4 5
2 3 4 5
3 4 5 6
3 4 5 6
Option 3
Can also use np.array in iloc
i = np.arange(len(df))
idx = np.append(i[:-2], i[-2:].repeat(2))
df.iloc[idx]
A B C
0 1 2 3
1 2 3 4
2 3 4 5
2 3 4 5
3 4 5 6
3 4 5 6