Update microservice.R

[LueJian]

Input data type persistence and null value persistence.

What this PR does / why we need it:

Input data type persistence

In all endpoint functions, if there are character and numeric value in input data simultaneously, the default of fromJSON(json) always convert numeric value to character type, therefore, the data type of columns in dataframe will be wrong after create_dataframe(jdf).

if the input data is like that:

json={"data":{"name":["col_must_be_char", "col_must_be_num"], "ndarray":[["A",12],[ "B",20]]}}

the data schema after fromJSON(json) now:

the data schema after create_dataframe(jdf) now:

expect data schema after create_dataframe(jdf):

The reason is that the outcome of fromJSON(json) will be "matrix" class, but the matrix in R only been allowed one data type at the same time. By adding an argument simplifyVector = False to fromJSON(json) can avoid that because the outcome of fromJSON(json, simplifyVector = False) will be "list" class:

Then we should add rbind() and lappy() into create_dataframe() to combine those list value and add an argument stringsAsFactors = False in data.frame() to avoid character data type transform to Factor automatically, because it always transform string to Factor using data.frame() by default in R. Therefore, we can get expect dataframe schema:

Convert input NULL value to NA

In general, we always express missing value by "" (string) and null (numeric). If we edit the script like demonstrate above, the null value (numeric missing value) will be convert to "NULL" after fromJSON(json, simplifyVectors=False) originally, so we have to add df[df == "NULL"] <- NA in create_dataframe() to replace NULL by NA.

if the input data is like that: (with null)
json={"data":{"name":["col_must_be_char", "col_must_be_num"], "ndarray":[["A",12],[ "",null]]}}

the outcome of fromJSON(json, simplifyVectors=False) and create_dataframe() without replace NULL by NA:

the outcome of fromJSON(json, simplifyVectors=False) and create_dataframe() with replace NULL by NA:

Convert response NA value to null

Like descriptions above, in general, we always express missing value by "" (string) and null (numeric), so we have to add an argument na = null to the toJSON() function in create_response(), then the NA in output will be null.

Which issue(s) this PR fixes:

Fixes #

Special notes for your reviewer:

Does this PR introduce a user-facing change?:

[seldondev]

Hi @LueJian. Thanks for your PR.

I'm waiting for a SeldonIO member to verify that this patch is reasonable to test. If it is, they should reply with /ok-to-test on its own line. Until that is done, I will not automatically test new commits in this PR, but the usual testing commands by org members will still work. Regular contributors should join the org to skip this step.

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[ukclivecox]

/ok-to-test

[ukclivecox]

@LueJian Thanks for this! This is great. It would be great to provide some better examples of real R use cases in the docs in a future PR.

[seldondev]

Tue Aug 4 06:31:11 UTC 2020
The logs for [lint] [2] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2239/2.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2239 --build=2

[seldondev]

Tue Aug 4 06:31:16 UTC 2020
The logs for [pr-build] [1] will show after the pipeline context has finished.
https://github.com/SeldonIO/seldon-core/blob/gh-pages/jenkins-x/logs/SeldonIO/seldon-core/PR-2239/1.log

impatient try
jx get build logs SeldonIO/seldon-core/PR-2239 --build=1

[ukclivecox]

/approve

[seldondev]

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