Replacing Values in a Frame
---------------------------

This example shows how to replace numeric values in a frame of data. Note that it is currently not possible to replace categorical value in a column.

.. tabs::
   .. code-tab:: r R

        library(h2o)
        h2o.init()

        # Upload the iris dataset
        path <- "http://h2o-public-test-data.s3.amazonaws.com/smalldata/iris/iris_wheader.csv"
        df <- h2o.importFile(path)

        # Replace a single numerical datum. Note that columns and rows start at 1,
        # so in the example below, the value in the 14th row and 2nd column will be set to 2.0.
        df[14, 2] <- 2.0

        # Replace a whole column. The example below multiplies all values in the second column by 3. 
        df[, 1] <- 3 * df[, 1]

        # Replace by row mask. The example below searches for value less than 4.4 in the 
        # sepal_len column and replaces those values with 4.6. 
        df[df[, "sepal_len"] <- 4.4, "sepal_len"] <- 4.6

        # Replace using ifelse. Similar to the previous example, 
        # this replaces values less than 4.6 with 4.6. 
        df[, "sepal_len"] <- h2o.ifelse(df[, "sepal_len"] < 4.4, 4.6, df[, "sepal_len"])

        # Replace missing values with 0 
        df[is.na(df[, "sepal_len"]), "sepal_len"] <- 0

        # Alternative with ifelse 
        df[, "sepal_len"] <- h2o.ifelse(is.na(df[, "sepal_len"]), 0, df[, "sepal_len"])

   .. code-tab:: python

        import h2o
        h2o.init()
        path = "http://h2o-public-test-data.s3.amazonaws.com/smalldata/iris/iris_wheader.csv"
        df = h2o.import_file(path=path)

        # Replace a single numerical datum. Note that columns and rows start at 0.
        # so in the example below, the value in the 15th row and 3rd column will be set to 2.0.
        df[14,2] = 2.0

        # Replace a whole column. The example below multiplies all values in the first column by 3.
        df[0] = 3*df[0]

        # Replace by row mask. The example below searches for value less than 4.6 in the 
        # sepal_len column and replaces those values with 4.6.
        df[df["sepal_len"] < 4.6, "sepal_len"] = 4.6

        # Replace using ifelse. Similar to the previous example, this replaces values less than 4.6 with 4.6. 
        df["sepal_len"] = (df["sepal_len"] < 4.6).ifelse(4.6, df["sepal_len"])

        # Replace missing values with 0.
        df[df["sepal_len"].isna(), "sepal_len"] = 0

        # Alternative with ifelse. Note the parantheses. 
        df["sepal_len"] = (df["sepal_len"].isna()).ifelse(0, df["sepal_len"])