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Add cumulative sum column to attribute table

How to add a new column in attribute table with attribute with indexes of another max-min ordered attribute field?Is it possible to sort the features by an attribute programmatically?Populate empty attribute table from constantly growing CSV in QGISGrouping by attribute sum in QGIS?Getting number of objects in attribute table using PyQGIS?Calculating sum of parts of column based on another column using QGIS Field Calculator?Changing Number values to specific text in Attribute table (QGIS)Restoring attribute table order to original in QGIS?Creating column in attribute table from summarised fields using QGIS?Sum fields in ArcGIS

3

1

I have an attribute table in QGIS in which I would like to calculate the cumulative sum. The table is sorted by N (number of fatalities) and I would like to calculate the cumulative sum on F (frequency of accident), i.e. F_cumulative should be a sum of the current row and the rows above. How should I do this? Can I use a formula in the field calculator?

qgis table sum

share|improve this question

edited 1 hour ago

underdark♦

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asked yesterday

Robert KRobert K

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New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
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• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Welcome to GIS SE. As a new user, please be sure to take the short tour to learn about this site's focused Q&A format.
  
  – Andy
  yesterday
  

  
  
  
  

add a comment | 

3

1

I have an attribute table in QGIS in which I would like to calculate the cumulative sum. The table is sorted by N (number of fatalities) and I would like to calculate the cumulative sum on F (frequency of accident), i.e. F_cumulative should be a sum of the current row and the rows above. How should I do this? Can I use a formula in the field calculator?

qgis table sum

share|improve this question

edited 1 hour ago

underdark♦

68.3k13177342

asked yesterday

Robert KRobert K

161

New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Welcome to GIS SE. As a new user, please be sure to take the short tour to learn about this site's focused Q&A format.
  
  – Andy
  yesterday
  

  
  
  
  

add a comment | 

I have an attribute table in QGIS in which I would like to calculate the cumulative sum. The table is sorted by N (number of fatalities) and I would like to calculate the cumulative sum on F (frequency of accident), i.e. F_cumulative should be a sum of the current row and the rows above. How should I do this? Can I use a formula in the field calculator?

qgis table sum

share|improve this question

edited 1 hour ago

underdark♦

68.3k13177342

asked yesterday

Robert KRobert K

161

New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 1 hour ago

underdark♦

68.3k13177342

asked yesterday

Robert KRobert K

161

New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

share|improve this question

edited 1 hour ago

underdark♦

68.3k13177342

asked yesterday

Robert KRobert K

161

New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

edited 1 hour ago

underdark♦

68.3k13177342

edited 1 hour ago

underdark♦

68.3k13177342

asked yesterday

Robert KRobert K

161

New contributor

Robert K is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.

asked yesterday

Robert KRobert K

161

1 Answer
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6

It can be done with an expression. Bear in mind this only works if the original table is already ordered with N descending as feature IDs increase. To get past NULL values ruining the calculation, first change the values in your cumulative field to 0 with the field calculator. Then, again in the field calculator, write this expression (modifying the relevant layer/field names):

attribute($currentfeature, 'your_frequency_field') + attribute(get_feature_by_id('your_layer', if($id = 1, $id, $id-1)), 'your_cumulative_field')

This will calculate a cumulative sum in order of feature IDs by fetching the frequency field attribute value of the currently evaluated feature and adding the cumulative frequency field attribute value of the previous feature (with the exception of feature ID = 1 which will fetch its own value: 0).

With a quick mockup of your data, this was my result summing on F and F_cum:

share|improve this answer

edited 4 hours ago

answered yesterday

Gabriel C.Gabriel C.

1,287320

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks, but I want to calculate the cumulative sum of the current row and ALL the rows above. In Excel I calculate it as a sum of F on the current row with F_cumulative on the row above. I tried to change your expression to do this in QGIS but all I get is NULL values. Any suggestions on how I can do this?
  
  – Robert K
  8 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @RobertK I modified the answer to address the issues.
  
  – Gabriel C.
  4 hours ago
  

  
  
  
  

add a comment | 

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6

It can be done with an expression. Bear in mind this only works if the original table is already ordered with N descending as feature IDs increase. To get past NULL values ruining the calculation, first change the values in your cumulative field to 0 with the field calculator. Then, again in the field calculator, write this expression (modifying the relevant layer/field names):

attribute($currentfeature, 'your_frequency_field') + attribute(get_feature_by_id('your_layer', if($id = 1, $id, $id-1)), 'your_cumulative_field')

This will calculate a cumulative sum in order of feature IDs by fetching the frequency field attribute value of the currently evaluated feature and adding the cumulative frequency field attribute value of the previous feature (with the exception of feature ID = 1 which will fetch its own value: 0).

With a quick mockup of your data, this was my result summing on F and F_cum:

share|improve this answer

edited 4 hours ago

answered yesterday

Gabriel C.Gabriel C.

1,287320

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks, but I want to calculate the cumulative sum of the current row and ALL the rows above. In Excel I calculate it as a sum of F on the current row with F_cumulative on the row above. I tried to change your expression to do this in QGIS but all I get is NULL values. Any suggestions on how I can do this?
  
  – Robert K
  8 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @RobertK I modified the answer to address the issues.
  
  – Gabriel C.
  4 hours ago
  

  
  
  
  

add a comment | 

6

It can be done with an expression. Bear in mind this only works if the original table is already ordered with N descending as feature IDs increase. To get past NULL values ruining the calculation, first change the values in your cumulative field to 0 with the field calculator. Then, again in the field calculator, write this expression (modifying the relevant layer/field names):

attribute($currentfeature, 'your_frequency_field') + attribute(get_feature_by_id('your_layer', if($id = 1, $id, $id-1)), 'your_cumulative_field')

This will calculate a cumulative sum in order of feature IDs by fetching the frequency field attribute value of the currently evaluated feature and adding the cumulative frequency field attribute value of the previous feature (with the exception of feature ID = 1 which will fetch its own value: 0).

With a quick mockup of your data, this was my result summing on F and F_cum:

share|improve this answer

edited 4 hours ago

answered yesterday

Gabriel C.Gabriel C.

1,287320

• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  Thanks, but I want to calculate the cumulative sum of the current row and ALL the rows above. In Excel I calculate it as a sum of F on the current row with F_cumulative on the row above. I tried to change your expression to do this in QGIS but all I get is NULL values. Any suggestions on how I can do this?
  
  – Robert K
  8 hours ago
  
  
  

  
  
  
  


• 
  
  
  

  
  

  
  
  
  
  
  

  
  
  @RobertK I modified the answer to address the issues.
  
  – Gabriel C.
  4 hours ago
  

  
  
  
  

add a comment | 

It can be done with an expression. Bear in mind this only works if the original table is already ordered with N descending as feature IDs increase. To get past NULL values ruining the calculation, first change the values in your cumulative field to 0 with the field calculator. Then, again in the field calculator, write this expression (modifying the relevant layer/field names):

attribute($currentfeature, 'your_frequency_field') + attribute(get_feature_by_id('your_layer', if($id = 1, $id, $id-1)), 'your_cumulative_field')

This will calculate a cumulative sum in order of feature IDs by fetching the frequency field attribute value of the currently evaluated feature and adding the cumulative frequency field attribute value of the previous feature (with the exception of feature ID = 1 which will fetch its own value: 0).

With a quick mockup of your data, this was my result summing on F and F_cum:

share|improve this answer

edited 4 hours ago

answered yesterday

Gabriel C.Gabriel C.

1,287320

share|improve this answer

edited 4 hours ago

answered yesterday

Gabriel C.Gabriel C.

1,287320

answered yesterday

Gabriel C.Gabriel C.

1,287320

answered yesterday

Gabriel C.Gabriel C.

1,287320