Cannot filter for strings

[forgetso]

Have you tried latest version of polars?

• yes
• no

What version of polars are you using?

nodejs-polars@0.6.0

What operating system are you using polars on?

Linux 5.4.0-132-generic #148-Ubuntu

What node version are you using

node --version
v16.13.2

Describe your bug.

Cannot filter for string values

What are the steps to reproduce the behavior?

> df = pl.DataFrame({"foo": ["a", "b", "c"]})
Proxy [
  shape: (3, 1)
  ┌─────┐
  │ foo │
  │ --- │
  │ str │
  ╞═════╡
  │ a   │
  ├╌╌╌╌╌┤
  │ b   │
  ├╌╌╌╌╌┤
  │ c   │
  └─────┘,
  {
    get: [Function: get],
    set: [Function: set],
    has: [Function: has],
    ownKeys: [Function: ownKeys],
    getOwnPropertyDescriptor: [Function: getOwnPropertyDescriptor]
  }
]
> df.filter(pl.col("foo").eq("b"))
Uncaught Error: Not found: b
    at Object.collectSync (/home/user/dev/workspaces/node_modules/nodejs-polars/bin/lazy/dataframe.js:62:53)
    at Proxy.filter (/home/user/dev/workspaces/node_modules/nodejs-polars/bin/dataframe.js:155:18) {
  code: 'GenericFailure'
}

What is the actual behavior?

The filter fails

What is the expected behavior?

The filter should succeed

Additional Info

You can get around this error by placing the string value in a series

> df = pl.DataFrame({"foo": ["a", "b", "c"]})
Proxy [
  shape: (3, 1)
  ┌─────┐
  │ foo │
  │ --- │
  │ str │
  ╞═════╡
  │ a   │
  ├╌╌╌╌╌┤
  │ b   │
  ├╌╌╌╌╌┤
  │ c   │
  └─────┘,
  {
    get: [Function: get],
    set: [Function: set],
    has: [Function: has],
    ownKeys: [Function: ownKeys],
    getOwnPropertyDescriptor: [Function: getOwnPropertyDescriptor]
  }
]
> df.filter(pl.col("foo").eq(pl.Series(["b"])))
Proxy [
  shape: (1, 1)
  ┌─────┐
  │ foo │
  │ --- │
  │ str │
  ╞═════╡
  │ b   │
  └─────┘,
  {
    get: [Function: get],
    set: [Function: set],
    has: [Function: has],
    ownKeys: [Function: ownKeys],
    getOwnPropertyDescriptor: [Function: getOwnPropertyDescriptor]
  }
]

[universalmind303]

when using strings, you need to use lit

df.filter(pl.col("foo").eq(pl.lit("b"))

[daolanfler]

I think the filter api's doc needs an update. it's not using pl.lit when comparing strings ....

[badele]

I'm using Polars with JavaScript (Deno). I spent a considerable amount of time searching through the documentation before stumbling upon this issue (it was the last test I performed before deciding to stop using Polars).

It seems necessary to either create an alias like compareString or clearly state in the documentation that, since the Polar version for Node.js, it is now required to use the following code:

const scan = await pl.scanCSV("database/.export/symbols_history.csv", {
  sep: ";",
  quoteChar: '"',
  parseDates: true,
}).select(["SYMBOL", "DATE", "Industry", "price"])
  .filter(
    pl.col("SYMBOL").eq(pl.lit("AI")),
  )
  .collect();

This could prevent any confusion and facilitate the transition to the new Polar practices."