tech.tablesaw.api.StringColumn Maven / Gradle / Ivy
/*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package tech.tablesaw.api;
import static com.google.common.base.Preconditions.checkArgument;
import static tech.tablesaw.api.ColumnType.*;
import it.unimi.dsi.fastutil.ints.IntComparator;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collection;
import java.util.Iterator;
import java.util.List;
import java.util.Set;
import java.util.stream.Stream;
import tech.tablesaw.columns.AbstractColumnParser;
import tech.tablesaw.columns.Column;
import tech.tablesaw.columns.strings.AbstractStringColumn;
import tech.tablesaw.columns.strings.ByteDictionaryMap;
import tech.tablesaw.columns.strings.DictionaryMap;
import tech.tablesaw.columns.strings.NoKeysAvailableException;
import tech.tablesaw.columns.strings.StringColumnType;
import tech.tablesaw.selection.BitmapBackedSelection;
import tech.tablesaw.selection.Selection;
/**
* A column that contains String values. They are assumed to be 'categorical' rather than free-form
* text, so are stored in an encoding that takes advantage of the expected repetition of string
* values.
*
* Because the MISSING_VALUE for this column type is an empty string, there is little or no need
* for special handling of missing values in this class's methods.
*/
public class StringColumn extends AbstractStringColumn {
// a bidirectional map of keys to backing string values.
private DictionaryMap lookupTable = new ByteDictionaryMap();
private final IntComparator rowComparator =
(i, i1) -> {
String f1 = get(i);
String f2 = get(i1);
return f1.compareTo(f2);
};
public static boolean valueIsMissing(String string) {
return StringColumnType.valueIsMissing(string);
}
/** {@inheritDoc} */
@Override
public StringColumn appendMissing() {
lookupTable.appendMissing();
return this;
}
/** {@inheritDoc} */
@Override
public int valueHash(int rowNumber) {
return get(rowNumber).hashCode();
}
/** {@inheritDoc} */
@Override
public boolean equals(int rowNumber1, int rowNumber2) {
return getDictionary().getKeyAtIndex(rowNumber1) == getDictionary().getKeyAtIndex(rowNumber2);
}
public static StringColumn create(String name) {
return new StringColumn(name);
}
public static StringColumn create(String name, String... strings) {
return new StringColumn(name, strings);
}
public static StringColumn create(String name, Collection strings) {
return new StringColumn(name, strings);
}
public static StringColumn createInternal(String name, DictionaryMap map) {
return new StringColumn(name, map);
}
public static StringColumn create(String name, int size) {
StringColumn column = new StringColumn(name, new ArrayList<>(size));
for (int i = 0; i < size; i++) {
column.appendMissing();
}
return column;
}
public static StringColumn create(String name, Stream stream) {
StringColumn column = create(name);
stream.forEach(column::append);
return column;
}
private StringColumn(String name, Collection strings) {
super(StringColumnType.instance(), name, StringColumnType.DEFAULT_PARSER);
for (String string : strings) {
append(string);
}
}
private StringColumn(String name, DictionaryMap map) {
super(StringColumnType.instance(), name, StringColumnType.DEFAULT_PARSER);
lookupTable = map;
}
private StringColumn(String name) {
super(StringColumnType.instance(), name, StringColumnType.DEFAULT_PARSER);
}
private StringColumn(String name, String[] strings) {
super(StringColumnType.instance(), name, StringColumnType.DEFAULT_PARSER);
for (String string : strings) {
append(string);
}
}
/** {@inheritDoc} */
@Override
public boolean isMissing(int rowNumber) {
return lookupTable.isMissing(rowNumber);
}
/** {@inheritDoc} */
@Override
public StringColumn emptyCopy() {
StringColumn empty = create(name());
empty.setPrintFormatter(getPrintFormatter());
return empty;
}
/** {@inheritDoc} */
@Override
public StringColumn emptyCopy(int rowSize) {
return create(name(), rowSize);
}
/** {@inheritDoc} */
@Override
public void sortAscending() {
lookupTable.sortAscending();
}
/** {@inheritDoc} */
@Override
public void sortDescending() {
lookupTable.sortDescending();
}
/**
* Returns the number of elements (a.k.a. rows or cells) in the column
*
* @return size as int
*/
@Override
public int size() {
return lookupTable.size();
}
/**
* Returns the value at rowIndex in this column. The index is zero-based.
*
* @param rowIndex index of the row
* @return value as String
* @throws IndexOutOfBoundsException if the given rowIndex is not in the column
*/
@Override
public String get(int rowIndex) {
return lookupTable.getValueForIndex(rowIndex);
}
/**
* Returns a List<String> representation of all the values in this column
*
* NOTE: Unless you really need a string consider using the column itself for large datasets as
* it uses much less memory
*
* @return values as a list of String.
*/
@Override
public List asList() {
List strings = new ArrayList<>();
for (String category : this) {
strings.add(category);
}
return strings;
}
/** {@inheritDoc} */
@Override
public Table summary() {
Table summary = Table.create(this.name());
StringColumn measure = StringColumn.create("Measure");
StringColumn value = StringColumn.create("Value");
summary.addColumns(measure);
summary.addColumns(value);
measure.append("Count");
value.append(String.valueOf(size()));
measure.append("Unique");
value.append(String.valueOf(countUnique()));
Table countByCategory = countByCategory().sortDescendingOn("Count");
measure.append("Top");
value.append(countByCategory.stringColumn("Category").getString(0));
measure.append("Top Freq.");
value.appendObj(countByCategory.intColumn("Count").getString(0));
return summary;
}
/** {@inheritDoc} */
@Override
public Table countByCategory() {
return lookupTable.countByCategory(name());
}
/** {@inheritDoc} */
@Override
public void clear() {
lookupTable.clear();
}
/** {@inheritDoc} */
@Override
public StringColumn lead(int n) {
StringColumn column = lag(-n);
column.setName(name() + " lead(" + n + ")");
return column;
}
/** {@inheritDoc} */
@Override
public StringColumn lag(int n) {
StringColumn copy = emptyCopy();
copy.setName(name() + " lag(" + n + ")");
if (n >= 0) {
for (int m = 0; m < n; m++) {
copy.appendMissing();
}
for (int i = 0; i < size(); i++) {
if (i + n >= size()) {
break;
}
copy.append(get(i));
}
} else {
for (int i = -n; i < size(); i++) {
copy.append(get(i));
}
for (int m = 0; m > n; m--) {
copy.appendMissing();
}
}
return copy;
}
/**
* Conditionally update this column, replacing current values with newValue for all rows where the
* current value matches the selection criteria
*
* Examples: myCatColumn.set(myCatColumn.isEqualTo("Cat"), "Dog"); // no more cats
* myCatColumn.set(myCatColumn.valueIsMissing(), "Fox"); // no more missing values
*/
@Override
public StringColumn set(Selection rowSelection, String newValue) {
for (int row : rowSelection) {
set(row, newValue);
}
return this;
}
/** {@inheritDoc} */
@Override
public StringColumn set(int rowIndex, String stringValue) {
if (stringValue == null) {
return setMissing(rowIndex);
}
try {
lookupTable.set(rowIndex, stringValue);
} catch (NoKeysAvailableException ex) {
lookupTable = lookupTable.promoteYourself();
try {
lookupTable.set(rowIndex, stringValue);
} catch (NoKeysAvailableException e) {
// this can't happen
throw new IllegalStateException(e);
}
}
return this;
}
/** {@inheritDoc} */
@Override
public int countUnique() {
return lookupTable.countUnique();
}
/**
* Returns true if this column contains a cell with the given string, and false otherwise
*
* @param aString the value to look for
* @return true if contains, false otherwise
*/
@Override
public boolean contains(String aString) {
return firstIndexOf(aString) >= 0;
}
/** {@inheritDoc} */
@Override
public StringColumn setMissing(int i) {
return set(i, StringColumnType.missingValueIndicator());
}
/**
* Add all the strings in the list to this column
*
* @param stringValues a list of values
*/
public StringColumn addAll(List stringValues) {
for (String stringValue : stringValues) {
append(stringValue);
}
return this;
}
/** {@inheritDoc} */
@Override
public StringColumn appendCell(String object) {
return appendCell(object, parser());
}
/** {@inheritDoc} */
@Override
public StringColumn appendCell(String object, AbstractColumnParser parser) {
return appendObj(parser.parse(object));
}
/** {@inheritDoc} */
@Override
public IntComparator rowComparator() {
return rowComparator;
}
/** {@inheritDoc} */
@Override
public boolean isEmpty() {
return lookupTable.size() == 0;
}
/** {@inheritDoc} */
@Override
public Selection isEqualTo(String string) {
return lookupTable.isEqualTo(string);
}
/** {@inheritDoc} */
@Override
public Selection isNotEqualTo(String string) {
return lookupTable.isNotEqualTo(string);
}
/**
* Returns a list of boolean columns suitable for use as dummy variables in, for example,
* regression analysis, select a column of categorical data must be encoded as a list of columns,
* such that each column represents a single category and indicates whether it is present (1) or
* not present (0)
*
* @return a list of {@link BooleanColumn}
*/
public List getDummies() {
return lookupTable.getDummies();
}
/**
* Returns a new Column containing all the unique values in this column
*
* @return a column with unique values.
*/
@Override
public StringColumn unique() {
List strings = new ArrayList<>(lookupTable.asSet());
return StringColumn.create(name() + " Unique values", strings);
}
public DoubleColumn asDoubleColumn() {
return DoubleColumn.create(this.name(), asDoubleArray());
}
/** {@inheritDoc} */
@Override
public StringColumn where(Selection selection) {
return subset(selection.toArray());
}
/** {@inheritDoc} */
@Override
public StringColumn copy() {
StringColumn newCol = create(name(), size());
int r = 0;
for (String string : this) {
newCol.set(r, string);
r++;
}
newCol.setPrintFormatter(getPrintFormatter());
return newCol;
}
/** {@inheritDoc} */
@Override
public StringColumn append(Column column) {
checkArgument(
column.type() == TEXT || column.type().equals(STRING),
"Column '%s' has type %s, but column '%s' has type %s.",
name(),
type(),
column.name(),
column.type());
final int size = column.size();
for (int i = 0; i < size; i++) {
append(column.getString(i));
}
return this;
}
/** Returns the count of missing values in this column */
@Override
public int countMissing() {
return lookupTable.countMissing();
}
/** {@inheritDoc} */
@Override
public StringColumn removeMissing() {
StringColumn noMissing = emptyCopy();
for (String v : this) {
if (!StringColumnType.valueIsMissing(v)) {
noMissing.append(v);
}
}
return noMissing;
}
/** {@inheritDoc} */
@Override
public Iterator iterator() {
return lookupTable.iterator();
}
public Set asSet() {
return lookupTable.asSet();
}
/** Returns the contents of the cell at rowNumber as a byte[] */
@Override
public byte[] asBytes(int rowNumber) {
return lookupTable.asBytes(rowNumber);
}
public double getDouble(int i) {
return (double)
lookupTable.uniqueValuesAt(lookupTable.firstIndexOf(lookupTable.getValueForIndex(i)))
- 1;
}
public double[] asDoubleArray() {
return Arrays.stream(lookupTable.asIntArray()).asDoubleStream().toArray();
}
/** Added for naming consistency with all other columns */
@Override
public StringColumn append(String value) {
try {
lookupTable.append(value);
} catch (NoKeysAvailableException ex) {
lookupTable = lookupTable.promoteYourself();
try {
lookupTable.append(value);
} catch (NoKeysAvailableException e) {
// this can't happen
throw new IllegalStateException(e);
}
}
return this;
}
/** {@inheritDoc} */
@Override
public StringColumn appendObj(Object obj) {
if (obj == null) {
return appendMissing();
}
if (!(obj instanceof String)) {
throw new IllegalArgumentException(
"Cannot append " + obj.getClass().getName() + " to StringColumn");
}
return append((String) obj);
}
/** {@inheritDoc} */
@Override
public Selection isIn(String... strings) {
return lookupTable.selectIsIn(strings);
}
/** {@inheritDoc} */
@Override
public Selection isIn(Collection strings) {
return lookupTable.selectIsIn(strings);
}
/** {@inheritDoc} */
@Override
public Selection isNotIn(String... strings) {
Selection results = new BitmapBackedSelection();
results.addRange(0, size());
results.andNot(isIn(strings));
return results;
}
/** {@inheritDoc} */
@Override
public Selection isNotIn(Collection strings) {
Selection results = new BitmapBackedSelection();
results.addRange(0, size());
results.andNot(isIn(strings));
return results;
}
public int firstIndexOf(String value) {
return lookupTable.firstIndexOf(value);
}
public int countOccurrences(String value) {
return lookupTable.countOccurrences(value);
}
/** {@inheritDoc} */
@Override
public String[] asObjectArray() {
return lookupTable.asObjectArray();
}
/** {@inheritDoc} */
@Override
public StringColumn asStringColumn() {
return copy();
}
public TextColumn asTextColumn() {
TextColumn textColumn = TextColumn.create(name(), size());
for (int i = 0; i < size(); i++) {
textColumn.set(i, get(i));
}
return textColumn;
}
/** For tablesaw internal use only */
public DictionaryMap getDictionary() {
return lookupTable;
}
}