The sample code below creates a summary.
If is possible to order the numbers associated with each "Type" in the output in descending order?
import pandas as pd
dicta={'a':['K','L','K','L','K','L','K','L'],
'b':['Type_x1','Type_y1','Type_z1','Type_x2','Type_y2','Type_z2','Type_x3','Type_y3'],
'c':[1,2,None,4,5,6,None,8]}
d=pd.DataFrame(dicta,columns=['a','b','c'])
k=d.pivot(index='a',columns='b',values='c')
k.apply(lambda x : x.name+": "+x.astype(str)).mask(k.isnull()).stack().groupby(level=0).apply(', '.join)
Sort them first before concatenating them.
import pandas as pd
dicta={'a':['K','L','K','L','K','L','K','L'],
'b':['Type_x1','Type_y1','Type_z1','Type_x2','Type_y2','Type_z2','Type_x3','Type_y3'],
'c':[1,2,None,4,5,6,None,8]}
d=pd.DataFrame(dicta,columns=['a','b','c'])
d = d.dropna().sort_values('c', ascending = False)
d['combined'] = d.apply(lambda x: x.b + ":" + str(x.c), axis = 1)
d.groupby('a')['combined'].agg(','.join)
Related
I am new to Pandas and would like to learn how to change alternate column names -
I have a dataframe which looks like this -
I would like to change the column names to be like this -
Any suggestion which apply a for loop would be helpful as I have 57 column names to change in the desired pattern.
A little verbose, but it works:
import pandas as pd
df = pd.DataFrame(columns = ['Time', 'Jolt1', 'Jolt2', 'Time', 'Jolt1', 'Jolt2', 'Time', 'Jolt1', 'Jolt2'])
c = 1
length = int(len(df.columns)/3)
my_list = []
for i in range(length):
my_list.append(['Time', 'Jolt'+str(c), 'Jolt'+str(c + 1)])
c = c + 1
df.columns = sum(my_list, [])
df.groupby('columns').apply(''.join()), join all the cells to a string.
This is for a junior dataprocessor. In the past, I've tried many ways.
import pandas as pd
data = {'key':['a','b','c','a','b','c','a'], 'profit':
[12,3,4,5,6,7,9],'income':['j','d','d','g','d','t','d']}
df = pd.DataFrame(data)
df = df.set_index(‘key’)
#df2 is expected result
data2 = {'a':['12j5g9d'],'b':['3d6d'],'c':['4d7t']}
df2 = pd.DataFrame(data2)
df2 = df2.set_index(‘key’)
Here's a simple solution, where we first translate the integers to strings and then concatenate profit and income, then finally we concatenate all strings under the same key:
data = {'key':['a','b','c','a','b','c','a'], 'profit':
[12,3,4,5,6,7,9],'income':['j','d','d','g','d','t','d']}
df = pd.DataFrame(data)
df['profit_income'] = df['profit'].apply(str) + df['income']
res = df.groupby('key')['profit_income'].agg(''.join)
print(res)
output:
key
a 12j5g9d
b 3d6d
c 4d7t
Name: profit_income, dtype: object
This question can be solved couple different ways:
First add an extra column by concatenating the profit and income columns.
import pandas as pd
data = {'key':['a','b','c','a','b','c','a'], 'profit':
[12,3,4,5,6,7,9],'income':['j','d','d','g','d','t','d']}
df = pd.DataFrame(data)
df = df.set_index('key')
df['profinc']=df['profit'].astype(str)+df['income']
1) Using sum
df2=df.groupby('key').profinc.sum()
2) Using apply and join
df2=df.groupby('key').profinc.apply(''.join)
Results from both of the above would be the same:
key
a 12j5g9d
b 3d6d
c 4d7t
I am trying to set an ARIMA model to some data, for this, I used 'autocorrelation_plot()' with my time series. It's generates however the error in the title.
I have an attribute table composed, among others, of a Date and time fiels.
I extracted them (after transforming the attribute table into a numpy table), put them in a 'datetime' variable and appended them all in a list:
O,A = [],[]
dt = datetime.strptime(dt1, "%Y/%m/%d %H:%M")
A.append(dt)
I tried then to create time series and printed them to be sure of the results:
data2 = pd.Series(A, O)
print data2
The results were satisfying, until I decided to auto-correlate :
Auto-correlation command :
autocorrelation_plot(data2)
After this command, it returns:
TypeError: ufunc add cannot use operands with types dtype('M8[ns]') and dtype('M8[ns]')
I guess it's due to the conversion of the datetime.strptime to a numpy ?
I tried to follow some suggestions from previous questions
index.to_pydatetime() , dtype, M8[ns] error ..., in vain.
Minimal reproducible example:
from pandas import datetime
from pandas import DataFrame
import pandas as pd
from matplotlib import pyplot as plt
from pandas.tools.plotting import autocorrelation_plot
arr = arcpy.da.TableToNumPyArray(inTable ,("PROVINCE","ZONE_CODE","MEAN", "Datetime","Time"))
arr_length = len(arr)
j = 1
O,A = [],[]
while j<=55: #I have 55 provinces
i = 0
while i<arr_length:
if arr[i][1]== j:
O.append(arr[i][2])
c = str(arr[i][3])
d = str(c[0:4]+"/"+c[5:7]+"/"+c[8:10])
t = str(arr[i][4])
if t=="10":
dt1 = str(d+" 10:00")
else:
dt1 = str(d+" 14:00")
dt = datetime.strptime(dt1, "%Y/%m/%d %H:%M")
A.append(dt)
i = i+1
data2 = pd.Series(A, O)
print data2
autocorrelation_plot(data2)
del A[:]
del O[:]
j += 1
Screenshot of the results:
results
I used this to solve my issue:
import matplotlib.dates as mpl_dates
df.reset_index(inplace=True)
df['Date']=df['Date'].apply(mpl_dates.date2num)
df = df.astype(float)
I found a solution, it can look barbaric, but it works!
I've just "recreated" pd.Series() with the pd.Series I had:
data2 = pd.Series(O, A)
autocorrelation_plot(pd.Series(data2))
plt.show()
In the below code, the dataframe df5 is not getting populated. I am just assigning the values to dataframe's columns and I have specified the column beforehand. When I print the dataframe, it returns an empty dataframe. Not sure whether I am missing something.
Any help would be appreciated.
import math
import pandas as pd
columns = ['ClosestLat','ClosestLong']
df5 = pd.DataFrame(columns=columns)
def distance(pt1, pt2):
return math.sqrt((pt1[0] - pt2[0])**2 + (pt1[1] - pt2[1])**2)
for pt1 in df1:
closestPoints = [pt1, df2[0]]
for pt2 in df2:
if distance(pt1, pt2) < distance(closestPoints[0], closestPoints[1]):
closestPoints = [pt1, pt2]
df5['ClosestLat'] = closestPoints[1][0]
df5['ClosestLat'] = closestPoints[1][0]
df5['ClosestLong'] = closestPoints[1][1]
print ("Point: " + str(closestPoints[0]) + " is closest to " + str(closestPoints[1]))
From the look of your code, you're trying to populate df5 with a list of latitudes and longitudes. However, you're making a couple mistakes.
The columns of pandas dataframes are Series, and hold some type of sequential data. So df5['ClosestLat'] = closestPoints[1][0] attempts to assign the entire column a single numerical value, and results in an empty column.
Even if the dataframe wasn't ignoring your attempts to assign a real number to the column, you would lose data because you are overwriting the column with each loop.
The Solution: Build a list of lats and longs, then insert into the dataframe.
import math
import pandas as pd
columns = ['ClosestLat','ClosestLong']
df5 = pd.DataFrame(columns=columns)
def distance(pt1, pt2):
return math.sqrt((pt1[0] - pt2[0])**2 + (pt1[1] - pt2[1])**2)
lats, lngs = [], []
for pt1 in df1:
closestPoints = [pt1, df2[0]]
for pt2 in df2:
if distance(pt1, pt2) < distance(closestPoints[0], closestPoints[1]):
closestPoints = [pt1, pt2]
lats.append(closestPoints[1][0])
lngs.append(closestPoints[1][1])
df['ClosestLat'] = pd.Series(lats)
df['ClosestLong'] = pd.Series(lngs)
In the following, func represents a function that uses multiple columns (with coupling across the group) and cannot operate directly on pandas.Series. The 0*d['x'] syntax was the lightest I could think of to force the conversion, but I think it's awkward.
Additionally, the resulting pandas.Series (s) still includes the group index, which must be removed before adding as a column to the pandas.DataFrame. The s.reset_index(...) index manipulation seems fragile and error-prone, so I'm curious if it can be avoided. Is there an idiom for doing this?
import pandas
import numpy
df = pandas.DataFrame(dict(i=[1]*8,j=[1]*4+[2]*4,x=list(range(4))*2))
df['y'] = numpy.sin(df['x']) + 1000*df['j']
df = df.set_index(['i','j'])
print('# df\n', df)
def func(d):
x = numpy.array(d['x'])
y = numpy.array(d['y'])
# I want to do math with x,y that cannot be applied to
# pandas.Series, so explicitly convert to numpy arrays.
#
# We have to return an appropriately-indexed pandas.Series
# in order for it to be admissible as a column in the
# pandas.DataFrame. Instead of simply "return x + y", we
# have to make the conversion.
return 0*d['x'] + x + y
s = df.groupby(df.index).apply(func)
# The Series is still adorned with the (unnamed) group index,
# which will prevent adding as a column of df due to
# Exception: cannot handle a non-unique multi-index!
s = s.reset_index(level=0, drop=True)
print('# s\n', s)
df['z'] = s
print('# df\n', df)
Instead of
0*d['x'] + x + y
you could use
pd.Series(x+y, index=d.index)
When using groupy-apply, instead of dropping the group key index using:
s = df.groupby(df.index).apply(func)
s = s.reset_index(level=0, drop=True)
df['z'] = s
you can tell groupby to drop the keys using the keyword parameter group_keys=False:
df['z'] = df.groupby(df.index, group_keys=False).apply(func)
import pandas as pd
import numpy as np
df = pd.DataFrame(dict(i=[1]*8,j=[1]*4+[2]*4,x=list(range(4))*2))
df['y'] = np.sin(df['x']) + 1000*df['j']
df = df.set_index(['i','j'])
def func(d):
x = np.array(d['x'])
y = np.array(d['y'])
return pd.Series(x+y, index=d.index)
df['z'] = df.groupby(df.index, group_keys=False).apply(func)
print(df)
yields
x y z
i j
1 1 0 1000.000000 1000.000000
1 1 1000.841471 1001.841471
1 2 1000.909297 1002.909297
1 3 1000.141120 1003.141120
2 0 2000.000000 2000.000000
2 1 2000.841471 2001.841471
2 2 2000.909297 2002.909297
2 3 2000.141120 2003.141120