quantize_fl()

The function quantize_fl() is a user-defined function (UDF) that bins metric columns. It quantizes metric columns to categorical labels, based on the K-Means algorithm.

Syntax

T | invoke quantize_fl(num_bins, in_cols, out_cols [, labels ])

Parameters

Function definition

You can define the function by either embedding its code as a query-defined function, or creating it as a stored function in your database, as follows:

Query-defined

Define the function using the following let statement. No permissions are required.

let quantize_fl=(tbl:(*), num_bins:int, in_cols:dynamic, out_cols:dynamic, labels:dynamic=dynamic(null))
{
    let kwargs = bag_pack('num_bins', num_bins, 'in_cols', in_cols, 'out_cols', out_cols, 'labels', labels);
    let code = ```if 1:
        
        from sklearn.preprocessing import KBinsDiscretizer
        
        num_bins = kargs["num_bins"]
        in_cols = kargs["in_cols"]
        out_cols = kargs["out_cols"]
        labels = kargs["labels"]
        
        result = df
        binner = KBinsDiscretizer(n_bins=num_bins, encode="ordinal", strategy="kmeans")
        df_in = df[in_cols]
        bdata = binner.fit_transform(df_in)
        if labels is None:
            for i in range(len(out_cols)):    # loop on each column and convert it to binned labels
                ii = np.round(binner.bin_edges_[i], 3)
                labels = [str(ii[j-1]) + '-' + str(ii[j]) for j in range(1, num_bins+1)]
                result.loc[:,out_cols[i]] = np.take(labels, bdata[:, i].astype(int))
        else:
            result[out_cols] = np.take(labels, bdata.astype(int))
    ```;
    tbl
    | evaluate python(typeof(*), code, kwargs)
};
// Write your query to use the function here.

Stored

Define the stored function once using the following .create function. Database User permissions are required.

.create function with (folder = "Packages\\ML", docstring = "Binning metric columns")
quantize_fl(tbl:(*), num_bins:int, in_cols:dynamic, out_cols:dynamic, labels:dynamic)
{
    let kwargs = bag_pack('num_bins', num_bins, 'in_cols', in_cols, 'out_cols', out_cols, 'labels', labels);
    let code = ```if 1:
        
        from sklearn.preprocessing import KBinsDiscretizer
        
        num_bins = kargs["num_bins"]
        in_cols = kargs["in_cols"]
        out_cols = kargs["out_cols"]
        labels = kargs["labels"]
        
        result = df
        binner = KBinsDiscretizer(n_bins=num_bins, encode="ordinal", strategy="kmeans")
        df_in = df[in_cols]
        bdata = binner.fit_transform(df_in)
        if labels is None:
            for i in range(len(out_cols)):    # loop on each column and convert it to binned labels
                ii = np.round(binner.bin_edges_[i], 3)
                labels = [str(ii[j-1]) + '-' + str(ii[j]) for j in range(1, num_bins+1)]
                result.loc[:,out_cols[i]] = np.take(labels, bdata[:, i].astype(int))
        else:
            result[out_cols] = np.take(labels, bdata.astype(int))
    ```;
    tbl
    | evaluate python(typeof(*), code, kwargs)
}

Example

The following example uses the invoke operator to run the function.

Query-defined

To use a query-defined function, invoke it after the embedded function definition.

let quantize_fl=(tbl:(*), num_bins:int, in_cols:dynamic, out_cols:dynamic, labels:dynamic=dynamic(null))
{
    let kwargs = bag_pack('num_bins', num_bins, 'in_cols', in_cols, 'out_cols', out_cols, 'labels', labels);
    let code = ```if 1:
        
        from sklearn.preprocessing import KBinsDiscretizer
        
        num_bins = kargs["num_bins"]
        in_cols = kargs["in_cols"]
        out_cols = kargs["out_cols"]
        labels = kargs["labels"]
        
        result = df
        binner = KBinsDiscretizer(n_bins=num_bins, encode="ordinal", strategy="kmeans")
        df_in = df[in_cols]
        bdata = binner.fit_transform(df_in)
        if labels is None:
            for i in range(len(out_cols)):    # loop on each column and convert it to binned labels
                ii = np.round(binner.bin_edges_[i], 3)
                labels = [str(ii[j-1]) + '-' + str(ii[j]) for j in range(1, num_bins+1)]
                result.loc[:,out_cols[i]] = np.take(labels, bdata[:, i].astype(int))
        else:
            result[out_cols] = np.take(labels, bdata.astype(int))
    ```;
    tbl
    | evaluate python(typeof(*), code, kwargs)
};
//
union 
(range x from 1 to 5 step 1),
(range x from 10 to 15 step 1),
(range x from 20 to 25 step 1)
| extend x_label='', x_bin=''
| invoke quantize_fl(3, pack_array('x'), pack_array('x_label'), pack_array('Low', 'Med', 'High'))
| invoke quantize_fl(3, pack_array('x'), pack_array('x_bin'), dynamic(null))

Stored

union 
(range x from 1 to 5 step 1),
(range x from 10 to 15 step 1),
(range x from 20 to 25 step 1)
| extend x_label='', x_bin=''
| invoke quantize_fl(3, pack_array('x'), pack_array('x_label'), pack_array('Low', 'Med', 'High'))
| invoke quantize_fl(3, pack_array('x'), pack_array('x_bin'), dynamic(null))

Output