reshape dataframe: columns to lines












0















I have a dataframe df_given [n, m] and I want to change the columns values into line values at each 3 rows.



import pandas as pd
df_test1 = pd.DataFrame({'A1': np.arange(1,4), 'B1': np.arange(10, 13), 'C1': np.arange(20, 23)})
df_test2 = pd.DataFrame({'A1': np.arange(11,14), 'B1': np.arange(100, 103), 'C1': np.arange(200, 203)})
df_given = pd.concat((df_test1, df_test2), axis =0)

df_desired = pd.DataFrame({'A': [1,10,20,11, 100, 200], 'B':[2,11, 21,12, 101, 201], 'C':[3,12,22,13, 102, 202]})
df_desired.head(10)

df_given.head(10)









share|improve this question

























  • Please paste the input and output in code format not images.

    – Mayank Porwal
    Oct 22 '18 at 14:23











  • I posted the whole code from the beginning. Should I delete the pictures?

    – Silvia
    Oct 22 '18 at 14:35











  • Code is fine, just replace your images with proper format.

    – Mayank Porwal
    Oct 22 '18 at 14:36













  • Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

    – Silvia
    Oct 22 '18 at 14:41
















0















I have a dataframe df_given [n, m] and I want to change the columns values into line values at each 3 rows.



import pandas as pd
df_test1 = pd.DataFrame({'A1': np.arange(1,4), 'B1': np.arange(10, 13), 'C1': np.arange(20, 23)})
df_test2 = pd.DataFrame({'A1': np.arange(11,14), 'B1': np.arange(100, 103), 'C1': np.arange(200, 203)})
df_given = pd.concat((df_test1, df_test2), axis =0)

df_desired = pd.DataFrame({'A': [1,10,20,11, 100, 200], 'B':[2,11, 21,12, 101, 201], 'C':[3,12,22,13, 102, 202]})
df_desired.head(10)

df_given.head(10)









share|improve this question

























  • Please paste the input and output in code format not images.

    – Mayank Porwal
    Oct 22 '18 at 14:23











  • I posted the whole code from the beginning. Should I delete the pictures?

    – Silvia
    Oct 22 '18 at 14:35











  • Code is fine, just replace your images with proper format.

    – Mayank Porwal
    Oct 22 '18 at 14:36













  • Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

    – Silvia
    Oct 22 '18 at 14:41














0












0








0








I have a dataframe df_given [n, m] and I want to change the columns values into line values at each 3 rows.



import pandas as pd
df_test1 = pd.DataFrame({'A1': np.arange(1,4), 'B1': np.arange(10, 13), 'C1': np.arange(20, 23)})
df_test2 = pd.DataFrame({'A1': np.arange(11,14), 'B1': np.arange(100, 103), 'C1': np.arange(200, 203)})
df_given = pd.concat((df_test1, df_test2), axis =0)

df_desired = pd.DataFrame({'A': [1,10,20,11, 100, 200], 'B':[2,11, 21,12, 101, 201], 'C':[3,12,22,13, 102, 202]})
df_desired.head(10)

df_given.head(10)









share|improve this question
















I have a dataframe df_given [n, m] and I want to change the columns values into line values at each 3 rows.



import pandas as pd
df_test1 = pd.DataFrame({'A1': np.arange(1,4), 'B1': np.arange(10, 13), 'C1': np.arange(20, 23)})
df_test2 = pd.DataFrame({'A1': np.arange(11,14), 'B1': np.arange(100, 103), 'C1': np.arange(200, 203)})
df_given = pd.concat((df_test1, df_test2), axis =0)

df_desired = pd.DataFrame({'A': [1,10,20,11, 100, 200], 'B':[2,11, 21,12, 101, 201], 'C':[3,12,22,13, 102, 202]})
df_desired.head(10)

df_given.head(10)






python pandas dataframe reshape






share|improve this question















share|improve this question













share|improve this question




share|improve this question








edited Nov 16 '18 at 3:23









Cœur

19k9114155




19k9114155










asked Oct 22 '18 at 14:19









SilviaSilvia

4510




4510













  • Please paste the input and output in code format not images.

    – Mayank Porwal
    Oct 22 '18 at 14:23











  • I posted the whole code from the beginning. Should I delete the pictures?

    – Silvia
    Oct 22 '18 at 14:35











  • Code is fine, just replace your images with proper format.

    – Mayank Porwal
    Oct 22 '18 at 14:36













  • Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

    – Silvia
    Oct 22 '18 at 14:41



















  • Please paste the input and output in code format not images.

    – Mayank Porwal
    Oct 22 '18 at 14:23











  • I posted the whole code from the beginning. Should I delete the pictures?

    – Silvia
    Oct 22 '18 at 14:35











  • Code is fine, just replace your images with proper format.

    – Mayank Porwal
    Oct 22 '18 at 14:36













  • Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

    – Silvia
    Oct 22 '18 at 14:41

















Please paste the input and output in code format not images.

– Mayank Porwal
Oct 22 '18 at 14:23





Please paste the input and output in code format not images.

– Mayank Porwal
Oct 22 '18 at 14:23













I posted the whole code from the beginning. Should I delete the pictures?

– Silvia
Oct 22 '18 at 14:35





I posted the whole code from the beginning. Should I delete the pictures?

– Silvia
Oct 22 '18 at 14:35













Code is fine, just replace your images with proper format.

– Mayank Porwal
Oct 22 '18 at 14:36







Code is fine, just replace your images with proper format.

– Mayank Porwal
Oct 22 '18 at 14:36















Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

– Silvia
Oct 22 '18 at 14:41





Ok, I don't understand what exactly do you mean. I will have to check the FAQ questions as I don't know what a proper format for images is.

– Silvia
Oct 22 '18 at 14:41












3 Answers
3






active

oldest

votes


















2














Using pd.concat with GroupBy:



df = df.reset_index(drop=True)

res = pd.concat((pd.DataFrame(df_slice.T.values, columns=df.columns.str[0])
for _, df_slice in df.groupby(df.index // 3)), ignore_index=True)

print(res)

A B C
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202


Explanation





  • df.reset_index(drop=True) resets the dataframe index to the regular pd.RangeIndex, i.e. 0, 1, 2, ..., n.


  • df.groupby(df.index // 3) groups the dataframe in chunks of 3 rows. We iterate over this GroupBy object in a generator comprehension.


  • df_slice.T.values transposes the 3 rows which constitute a slice and converts to a NumPy array. We feed this to pd.DataFrame to construct a dataframe from a NumPy array.


  • pd.concat takes an iterable of dataframes and combines them to construct a single dataframe.






share|improve this answer





















  • 1





    Seems like there is no better way :-(

    – Wen-Ben
    Oct 22 '18 at 14:42











  • Can you elaborate a bit on what the code is doing?

    – Silvia
    Oct 22 '18 at 14:53











  • @Silvia, Sure, added an explanation.

    – jpp
    Oct 22 '18 at 15:25



















2














IIUC



pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T
Out[997]:
0 1 2
A1 1 2 3
B1 10 11 12
C1 20 21 22
A1 11 12 13
B1 100 101 102
C1 200 201 202





share|improve this answer
























  • I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

    – Silvia
    Oct 22 '18 at 14:51






  • 1





    @Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

    – Wen-Ben
    Oct 22 '18 at 14:54











  • You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

    – Silvia
    Oct 22 '18 at 15:02



















1














One alternative using groupby, stack & unstack



df1 = df_given.assign(g=df_given.groupby(level=0).cumcount()).set_index('g',append=True)

df1 = df1.stack().unstack(0).reset_index(drop=True)

df1.columns = df_given.columns

print (df1)


A1 B1 C1
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202





share|improve this answer



















  • 1





    This version also works.

    – Silvia
    Oct 22 '18 at 15:03











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3 Answers
3






active

oldest

votes








3 Answers
3






active

oldest

votes









active

oldest

votes






active

oldest

votes









2














Using pd.concat with GroupBy:



df = df.reset_index(drop=True)

res = pd.concat((pd.DataFrame(df_slice.T.values, columns=df.columns.str[0])
for _, df_slice in df.groupby(df.index // 3)), ignore_index=True)

print(res)

A B C
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202


Explanation





  • df.reset_index(drop=True) resets the dataframe index to the regular pd.RangeIndex, i.e. 0, 1, 2, ..., n.


  • df.groupby(df.index // 3) groups the dataframe in chunks of 3 rows. We iterate over this GroupBy object in a generator comprehension.


  • df_slice.T.values transposes the 3 rows which constitute a slice and converts to a NumPy array. We feed this to pd.DataFrame to construct a dataframe from a NumPy array.


  • pd.concat takes an iterable of dataframes and combines them to construct a single dataframe.






share|improve this answer





















  • 1





    Seems like there is no better way :-(

    – Wen-Ben
    Oct 22 '18 at 14:42











  • Can you elaborate a bit on what the code is doing?

    – Silvia
    Oct 22 '18 at 14:53











  • @Silvia, Sure, added an explanation.

    – jpp
    Oct 22 '18 at 15:25
















2














Using pd.concat with GroupBy:



df = df.reset_index(drop=True)

res = pd.concat((pd.DataFrame(df_slice.T.values, columns=df.columns.str[0])
for _, df_slice in df.groupby(df.index // 3)), ignore_index=True)

print(res)

A B C
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202


Explanation





  • df.reset_index(drop=True) resets the dataframe index to the regular pd.RangeIndex, i.e. 0, 1, 2, ..., n.


  • df.groupby(df.index // 3) groups the dataframe in chunks of 3 rows. We iterate over this GroupBy object in a generator comprehension.


  • df_slice.T.values transposes the 3 rows which constitute a slice and converts to a NumPy array. We feed this to pd.DataFrame to construct a dataframe from a NumPy array.


  • pd.concat takes an iterable of dataframes and combines them to construct a single dataframe.






share|improve this answer





















  • 1





    Seems like there is no better way :-(

    – Wen-Ben
    Oct 22 '18 at 14:42











  • Can you elaborate a bit on what the code is doing?

    – Silvia
    Oct 22 '18 at 14:53











  • @Silvia, Sure, added an explanation.

    – jpp
    Oct 22 '18 at 15:25














2












2








2







Using pd.concat with GroupBy:



df = df.reset_index(drop=True)

res = pd.concat((pd.DataFrame(df_slice.T.values, columns=df.columns.str[0])
for _, df_slice in df.groupby(df.index // 3)), ignore_index=True)

print(res)

A B C
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202


Explanation





  • df.reset_index(drop=True) resets the dataframe index to the regular pd.RangeIndex, i.e. 0, 1, 2, ..., n.


  • df.groupby(df.index // 3) groups the dataframe in chunks of 3 rows. We iterate over this GroupBy object in a generator comprehension.


  • df_slice.T.values transposes the 3 rows which constitute a slice and converts to a NumPy array. We feed this to pd.DataFrame to construct a dataframe from a NumPy array.


  • pd.concat takes an iterable of dataframes and combines them to construct a single dataframe.






share|improve this answer















Using pd.concat with GroupBy:



df = df.reset_index(drop=True)

res = pd.concat((pd.DataFrame(df_slice.T.values, columns=df.columns.str[0])
for _, df_slice in df.groupby(df.index // 3)), ignore_index=True)

print(res)

A B C
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202


Explanation





  • df.reset_index(drop=True) resets the dataframe index to the regular pd.RangeIndex, i.e. 0, 1, 2, ..., n.


  • df.groupby(df.index // 3) groups the dataframe in chunks of 3 rows. We iterate over this GroupBy object in a generator comprehension.


  • df_slice.T.values transposes the 3 rows which constitute a slice and converts to a NumPy array. We feed this to pd.DataFrame to construct a dataframe from a NumPy array.


  • pd.concat takes an iterable of dataframes and combines them to construct a single dataframe.







share|improve this answer














share|improve this answer



share|improve this answer








edited Oct 22 '18 at 15:25

























answered Oct 22 '18 at 14:30









jppjpp

102k2165115




102k2165115








  • 1





    Seems like there is no better way :-(

    – Wen-Ben
    Oct 22 '18 at 14:42











  • Can you elaborate a bit on what the code is doing?

    – Silvia
    Oct 22 '18 at 14:53











  • @Silvia, Sure, added an explanation.

    – jpp
    Oct 22 '18 at 15:25














  • 1





    Seems like there is no better way :-(

    – Wen-Ben
    Oct 22 '18 at 14:42











  • Can you elaborate a bit on what the code is doing?

    – Silvia
    Oct 22 '18 at 14:53











  • @Silvia, Sure, added an explanation.

    – jpp
    Oct 22 '18 at 15:25








1




1





Seems like there is no better way :-(

– Wen-Ben
Oct 22 '18 at 14:42





Seems like there is no better way :-(

– Wen-Ben
Oct 22 '18 at 14:42













Can you elaborate a bit on what the code is doing?

– Silvia
Oct 22 '18 at 14:53





Can you elaborate a bit on what the code is doing?

– Silvia
Oct 22 '18 at 14:53













@Silvia, Sure, added an explanation.

– jpp
Oct 22 '18 at 15:25





@Silvia, Sure, added an explanation.

– jpp
Oct 22 '18 at 15:25













2














IIUC



pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T
Out[997]:
0 1 2
A1 1 2 3
B1 10 11 12
C1 20 21 22
A1 11 12 13
B1 100 101 102
C1 200 201 202





share|improve this answer
























  • I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

    – Silvia
    Oct 22 '18 at 14:51






  • 1





    @Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

    – Wen-Ben
    Oct 22 '18 at 14:54











  • You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

    – Silvia
    Oct 22 '18 at 15:02
















2














IIUC



pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T
Out[997]:
0 1 2
A1 1 2 3
B1 10 11 12
C1 20 21 22
A1 11 12 13
B1 100 101 102
C1 200 201 202





share|improve this answer
























  • I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

    – Silvia
    Oct 22 '18 at 14:51






  • 1





    @Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

    – Wen-Ben
    Oct 22 '18 at 14:54











  • You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

    – Silvia
    Oct 22 '18 at 15:02














2












2








2







IIUC



pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T
Out[997]:
0 1 2
A1 1 2 3
B1 10 11 12
C1 20 21 22
A1 11 12 13
B1 100 101 102
C1 200 201 202





share|improve this answer













IIUC



pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T
Out[997]:
0 1 2
A1 1 2 3
B1 10 11 12
C1 20 21 22
A1 11 12 13
B1 100 101 102
C1 200 201 202






share|improve this answer












share|improve this answer



share|improve this answer










answered Oct 22 '18 at 14:30









Wen-BenWen-Ben

119k83569




119k83569













  • I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

    – Silvia
    Oct 22 '18 at 14:51






  • 1





    @Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

    – Wen-Ben
    Oct 22 '18 at 14:54











  • You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

    – Silvia
    Oct 22 '18 at 15:02



















  • I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

    – Silvia
    Oct 22 '18 at 14:51






  • 1





    @Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

    – Wen-Ben
    Oct 22 '18 at 14:54











  • You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

    – Silvia
    Oct 22 '18 at 15:02

















I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

– Silvia
Oct 22 '18 at 14:51





I am pandas 0.23.0, and unfortunatelly this didn't work for me. The df is transposed, but I am getting still a (3,5) sdf shape

– Silvia
Oct 22 '18 at 14:51




1




1





@Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

– Wen-Ben
Oct 22 '18 at 14:54





@Silvia it is work , you just forget assign it back df=pd.concat([x for _,x in df_given.groupby((df_given.index==0).cumsum())],axis=1).T

– Wen-Ben
Oct 22 '18 at 14:54













You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

– Silvia
Oct 22 '18 at 15:02





You are very right. My mistake. I am sorry, I have accepted the other answer already, I just could gave you a +.

– Silvia
Oct 22 '18 at 15:02











1














One alternative using groupby, stack & unstack



df1 = df_given.assign(g=df_given.groupby(level=0).cumcount()).set_index('g',append=True)

df1 = df1.stack().unstack(0).reset_index(drop=True)

df1.columns = df_given.columns

print (df1)


A1 B1 C1
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202





share|improve this answer



















  • 1





    This version also works.

    – Silvia
    Oct 22 '18 at 15:03
















1














One alternative using groupby, stack & unstack



df1 = df_given.assign(g=df_given.groupby(level=0).cumcount()).set_index('g',append=True)

df1 = df1.stack().unstack(0).reset_index(drop=True)

df1.columns = df_given.columns

print (df1)


A1 B1 C1
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202





share|improve this answer



















  • 1





    This version also works.

    – Silvia
    Oct 22 '18 at 15:03














1












1








1







One alternative using groupby, stack & unstack



df1 = df_given.assign(g=df_given.groupby(level=0).cumcount()).set_index('g',append=True)

df1 = df1.stack().unstack(0).reset_index(drop=True)

df1.columns = df_given.columns

print (df1)


A1 B1 C1
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202





share|improve this answer













One alternative using groupby, stack & unstack



df1 = df_given.assign(g=df_given.groupby(level=0).cumcount()).set_index('g',append=True)

df1 = df1.stack().unstack(0).reset_index(drop=True)

df1.columns = df_given.columns

print (df1)


A1 B1 C1
0 1 2 3
1 10 11 12
2 20 21 22
3 11 12 13
4 100 101 102
5 200 201 202






share|improve this answer












share|improve this answer



share|improve this answer










answered Oct 22 '18 at 14:54









AbhiAbhi

2,540421




2,540421








  • 1





    This version also works.

    – Silvia
    Oct 22 '18 at 15:03














  • 1





    This version also works.

    – Silvia
    Oct 22 '18 at 15:03








1




1





This version also works.

– Silvia
Oct 22 '18 at 15:03





This version also works.

– Silvia
Oct 22 '18 at 15:03


















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