Read parquet file error

6 次查看（过去 30 天）
Christian
Christian 2021-8-17
评论： Yongjian Feng 2021-11-3
Hi,
I'm reading parquet files and facing some problems. For comparison the file was read with python using fastparquet with no errors.
The file contains 74 columns and already the output of parquetinfo shows that there is an issue with some of the columns, since the length of the variables doesn't match:
FileSize: 66748042
NumRowGroups: 1
RowGroupHeights: 233382
VariableNames: [1×31 string]
VariableTypes: [1×31 string]
VariableCompression: [1×74 string]
When reading the data with Matlab the following error occurs:
tbl = parquetread(fname)
Error using matlab.io.parquet.internal.makeParquetException>makeUnsupportedParquetTypeException (line 26)
To assign to or create a variable in a table, the number of rows must match the height of the table.
Error in matlab.io.parquet.internal.makeParquetException (line 10)
e = makeUnsupportedParquetTypeException(e, filename);
Error in parquetread (line 128)
e = makeParquetException(e, filename);
I've tried to access the data via the column name directly using the column names provided by parquetinfo. This works for some variables but for other variables it states that the variable is not a subset of the variablenames:
tbl = parquetread(fname ,'SelectedVariableNames','variableX');
Error using parquetread (line 124)
'SelectedVariableNames' value must be a unique subset of 'variable1, ....'
Using the list of variables in this error message delivers again the first error message
tbl = parquetread(fname ,'SelectedVariableNames','variable1');
me =
MException with properties:
identifier: 'MATLAB:table:RowDimensionMismatch'
message: 'To assign to or create a variable in a table, the number of rows must match the height of the table.'
cause: {}
stack: [3×1 struct]
Correction: []
The I tried to access the data via the column names coming from python. However, this gievs the error that the variable is not part of the variable list (see second error above)
In Python some of the column names contain a period like "name.name1". Can this be an issue in Matlab?
Any ideas on that?
Thanks a lot.
Christian

请先登录，再回答此问题。

采纳的回答

Yongjian Feng
Yongjian Feng 2021-8-18
matlab can call python script. Use python to read and then pass the data to matlab. Or use python to convert the data into CSV or json first and then use matlab to read.
  3 个评论
显示 1更早的评论
tim che
tim che 2021-11-3
could you please tell how to read file using python? I have this problem
Yongjian Feng
Yongjian Feng 2021-11-3
This looks like error shown in matlab, right? If so, maybe you need to make sure the python script can run successfully outside matlab first. Then figure out how to run it from matlab.

请先登录，再进行评论。

更多回答（0 个）

类别

在 Help Center 和 File Exchange 中查找有关 Call Python from MATLAB 的更多信息

标签

产品


版本

R2019b

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by