Python-Replace rows in a column using condition in other column using dictionary
2
A B
abc AN
abd BN
a01 CN
abc BN
a02 CN
I have a dataframe similar to above. For every B=CN,I want to replace corresponding row in A i.e a01,a02 with value from dictionary.
The dictionary is as follow:
d='a01':'ana','a02':'aza'
Whenever I'm trying to replace the values, it's giving incorrect result either the values are misplaced. I tried where clause as well but still missing something.
python-3.x pandas dataframe data-science
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
add a comment |
2
A B
abc AN
abd BN
a01 CN
abc BN
a02 CN
I have a dataframe similar to above. For every B=CN,I want to replace corresponding row in A i.e a01,a02 with value from dictionary.
The dictionary is as follow:
d='a01':'ana','a02':'aza'
Whenever I'm trying to replace the values, it's giving incorrect result either the values are misplaced. I tried where clause as well but still missing something.
python-3.x pandas dataframe data-science
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
1
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18
add a comment |
2
2
2
A B
abc AN
abd BN
a01 CN
abc BN
a02 CN
I have a dataframe similar to above. For every B=CN,I want to replace corresponding row in A i.e a01,a02 with value from dictionary.
The dictionary is as follow:
d='a01':'ana','a02':'aza'
Whenever I'm trying to replace the values, it's giving incorrect result either the values are misplaced. I tried where clause as well but still missing something.
python-3.x pandas dataframe data-science
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
A B
abc AN
abd BN
a01 CN
abc BN
a02 CN
I have a dataframe similar to above. For every B=CN,I want to replace corresponding row in A i.e a01,a02 with value from dictionary.
The dictionary is as follow:
d='a01':'ana','a02':'aza'
Whenever I'm trying to replace the values, it's giving incorrect result either the values are misplaced. I tried where clause as well but still missing something.
python-3.x pandas dataframe data-science
python-3.x pandas dataframe data-science
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
edited Nov 15 '18 at 9:52
Akhilesh Pandey
549313
549313
asked Nov 15 '18 at 5:23
VroJVroJ
255
asked Nov 15 '18 at 5:23
VroJVroJ
255
asked Nov 15 '18 at 5:23
VroJVroJ
255
255
1
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18
add a comment |
1
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18
1
1
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18
add a comment |
2 Answers
2
active
oldest
votes
1
In a single line in would look like this:
df.loc[df['B'].eq('CN'), 'A'] = df['A'].map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
Also you can use np.where:
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
Here is the whole code with np.where:
import pandas as pd
import numpy as np
df = pd.DataFrame('A': ['abc', 'abd', 'a01', 'abc', 'a02'],
'B': ['AN', 'BN', 'CN', 'BN', 'CN'])
d = 'a01': 'ana', 'a02': 'aza'
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
add a comment |
0
Use map to use the dictionary for mapping the values and loc to assign the values to the particular slice:
CN = df['B'] == 'CN'
df['A'].loc[CN] = df[CN].A.map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
1
In a single line in would look like this:
df.loc[df['B'].eq('CN'), 'A'] = df['A'].map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
Also you can use np.where:
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
Here is the whole code with np.where:
import pandas as pd
import numpy as np
df = pd.DataFrame('A': ['abc', 'abd', 'a01', 'abc', 'a02'],
'B': ['AN', 'BN', 'CN', 'BN', 'CN'])
d = 'a01': 'ana', 'a02': 'aza'
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
add a comment |
1
In a single line in would look like this:
df.loc[df['B'].eq('CN'), 'A'] = df['A'].map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
Also you can use np.where:
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
Here is the whole code with np.where:
import pandas as pd
import numpy as np
df = pd.DataFrame('A': ['abc', 'abd', 'a01', 'abc', 'a02'],
'B': ['AN', 'BN', 'CN', 'BN', 'CN'])
d = 'a01': 'ana', 'a02': 'aza'
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
add a comment |
1
1
1
In a single line in would look like this:
df.loc[df['B'].eq('CN'), 'A'] = df['A'].map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
Also you can use np.where:
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
Here is the whole code with np.where:
import pandas as pd
import numpy as np
df = pd.DataFrame('A': ['abc', 'abd', 'a01', 'abc', 'a02'],
'B': ['AN', 'BN', 'CN', 'BN', 'CN'])
d = 'a01': 'ana', 'a02': 'aza'
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
In a single line in would look like this:
df.loc[df['B'].eq('CN'), 'A'] = df['A'].map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
Also you can use np.where:
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
Here is the whole code with np.where:
import pandas as pd
import numpy as np
df = pd.DataFrame('A': ['abc', 'abd', 'a01', 'abc', 'a02'],
'B': ['AN', 'BN', 'CN', 'BN', 'CN'])
d = 'a01': 'ana', 'a02': 'aza'
df['A'] = np.where(df['B'].eq('CN'), df['A'].map(d), df['A'])
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
edited Nov 15 '18 at 14:27
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
answered Nov 15 '18 at 10:15
zipazipa
16.2k31638
16.2k31638
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
add a comment |
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
0n applying it,I get 'nan' for replaced values in A.
– VroJ
Nov 15 '18 at 14:22
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
@VroJ I've added code for your example and it works as intended.
– zipa
Nov 15 '18 at 14:27
thank you very much.
– VroJ
Nov 16 '18 at 22:42
thank you very much.
– VroJ
Nov 16 '18 at 22:42
add a comment |
0
Use map to use the dictionary for mapping the values and loc to assign the values to the particular slice:
CN = df['B'] == 'CN'
df['A'].loc[CN] = df[CN].A.map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
add a comment |
0
Use map to use the dictionary for mapping the values and loc to assign the values to the particular slice:
CN = df['B'] == 'CN'
df['A'].loc[CN] = df[CN].A.map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
add a comment |
0
0
0
Use map to use the dictionary for mapping the values and loc to assign the values to the particular slice:
CN = df['B'] == 'CN'
df['A'].loc[CN] = df[CN].A.map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
Use map to use the dictionary for mapping the values and loc to assign the values to the particular slice:
CN = df['B'] == 'CN'
df['A'].loc[CN] = df[CN].A.map(d)
df
A B
0 abc AN
1 abd BN
2 ana CN
3 abc BN
4 aza CN
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
answered Nov 15 '18 at 7:23
Franco PiccoloFranco Piccolo
1,591714
1,591714
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
add a comment |
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
0n applying it,I get 'nan' for replaced values in A.There is a warning "A value is trying to be set on a copy of a slice from a DataFrame".
– VroJ
Nov 15 '18 at 14:18
add a comment |
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1
Can you rephrase the question, specifically can you give more details about the "dataframe": is it a text file, array or some sort of data-structure? Maybe provide some existing code, MWE.
– Emil Vatai
Nov 15 '18 at 5:28
@EmilVatai There is a csv file with above dataframe.A and B are column of object type.I've to replace few values in rows of column A i.e a01 and a02 with values in dictionary d but the condition is only if B is equal to CN.
– VroJ
Nov 15 '18 at 6:00
pandas.DataFrame? That part of your question is very vague... You want to change the csv or the datastructure? Could you provide a MVE?
– Emil Vatai
Nov 15 '18 at 6:22
X=pd.read_csv('somefile.csv). A and B are columns in X.I've to replace few rows in A which have values a01 and a02 but only if the values in column B is BN.I've created a dictionary d whose value are to be used for replacing rows in A.For example: a01 should be replaced by ana only if rows in B have value equal to CN .Is it clear now?
– VroJ
Nov 15 '18 at 7:18