!2258 address some review comments on doc

Merge pull request !2258 from ZiruiWu/fix_api_doc

mindspore/ccsrc/dataset/engine/datasetops/build_vocab_op.cc

@@ -141,6 +141,11 @@ Status BuildVocabOp::CollectorThread() {
     }
   }
   int64_t num_words = std::min(static_cast<int64_t>(words.size()), top_k_);
+  if (num_words == 0) {
+    MS_LOG(WARNING) << "No word falls in the frequency range: (" << freq_range_.first << "," << freq_range_.second
+                    << ") vocab would be empty (except for special tokens).";
+  }
+
   // this would take the top-k most frequent words
   std::partial_sort(words.begin(), words.begin() + num_words, words.end(),
                     [this](const std::string &w1, const std::string &w2) {

mindspore/ccsrc/dataset/engine/datasetops/source/image_folder_op.cc

@@ -323,9 +323,7 @@ Status ImageFolderOp::PrescanWorkerEntry(int32_t worker_id) {
 // if mRecursive == false, don't go into folder of folders
 Status ImageFolderOp::RecursiveWalkFolder(Path *dir) {
   std::shared_ptr<Path::DirIterator> dir_itr = Path::DirIterator::OpenDirectory(dir);
-  if (dir_itr == nullptr) {
-    RETURN_STATUS_UNEXPECTED("Error encountered when indexing files");
-  }
+  RETURN_UNEXPECTED_IF_NULL(dir_itr);
   while (dir_itr->hasNext()) {
     Path subdir = dir_itr->next();
     if (subdir.IsDirectory()) {

mindspore/dataset/engine/__init__.py

@@ -32,6 +32,5 @@ __all__ = ["config", "ConfigurationManager", "zip",
            "ImageFolderDatasetV2", "MnistDataset",
            "MindDataset", "GeneratorDataset", "TFRecordDataset", "CLUEDataset",
            "ManifestDataset", "Cifar10Dataset", "Cifar100Dataset", "CelebADataset",
-           "VOCDataset", "CocoDataset", "TextFileDataset", "BuildVocabDataset", "Schema", "Schema",
-           "DistributedSampler", "PKSampler",
-           "RandomSampler", "SequentialSampler", "SubsetRandomSampler", "WeightedRandomSampler"]
+           "VOCDataset", "CocoDataset", "TextFileDataset", "Schema", "DistributedSampler",
+           "PKSampler", "RandomSampler", "SequentialSampler", "SubsetRandomSampler", "WeightedRandomSampler"]

mindspore/dataset/engine/datasets.py

@@ -42,8 +42,8 @@ from .iterators import DictIterator, TupleIterator
 from .validators import check_batch, check_shuffle, check_map, check_filter, check_repeat, check_skip, check_zip, \
     check_rename, check_numpyslicesdataset, \
     check_take, check_project, check_imagefolderdatasetv2, check_mnist_cifar_dataset, check_manifestdataset, \
-    check_tfrecorddataset, check_vocdataset, check_cocodataset, check_celebadataset, check_minddataset,\
-    check_generatordataset, check_sync_wait, check_zip_dataset, check_add_column, check_textfiledataset, check_concat,\
+    check_tfrecorddataset, check_vocdataset, check_cocodataset, check_celebadataset, check_minddataset, \
+    check_generatordataset, check_sync_wait, check_zip_dataset, check_add_column, check_textfiledataset, check_concat, \
     check_split, check_bucket_batch_by_length, check_cluedataset
 from ..core.datatypes import mstype_to_detype, mstypelist_to_detypelist
 
@@ -895,26 +895,7 @@ class Dataset:
         return ProjectDataset(self, columns)
 
     def build_vocab(self, vocab, columns, freq_range, top_k):
-        """
-        Build a vocab from a dataset. This would collect all the unique words in a dataset and return a vocab
-        which contains top_k most frequent words (if top_k is specified)
-        This function is not meant to be called directly by user. To build vocab, please use the function
-        text.Vocab.from_dataset()
-
-        Args:
-            vocab(Vocab): vocab object
-            columns(str or list, optional): column names to get words from. It can be a list of column names.
-            (Default is None where all columns will be used. If any column isn't string type, will return error)
-            freq_range(tuple, optional): A tuple of integers (min_frequency, max_frequency). Words within the frequency
-            range would be kept. 0 <= min_frequency <= max_frequency <= total_words. min_frequency/max_frequency
-            can be None, which corresponds to 0/total_words separately (default is None, all words are included)
-            top_k(int, optional): top_k > 0. Number of words to be built into vocab. top_k most frequent words are
-            taken. top_k is taken after freq_range. If not enough top_k, all words will be taken. (default is None
-            all words are included)
-
-        Returns:
-            BuildVocabDataset
-        """
+        """ Internal function for building a vocab"""
         return BuildVocabDataset(self, vocab, columns, freq_range, top_k)
 
     def apply(self, apply_func):
@@ -1468,6 +1449,7 @@ class DatasetOp(Dataset):
 
     # No need for __init__ since it is the same as the super's init
 
+
 class BucketBatchByLengthDataset(DatasetOp):
     """
     The result of applying BucketBatchByLength operator to the input dataset.
@@ -1608,7 +1590,7 @@ class BatchDataset(DatasetOp):
 
         Args:
              dataset (Dataset): dataset to be checked.
-             batchsize (int): batch size to notify.
+             batch_size (int): batch size to notify.
         """
         if isinstance(dataset, SyncWaitDataset):
             dataset.update_sync_batch_size(batch_size)
@@ -1646,7 +1628,7 @@ class BlockReleasePair:
 
     Args:
         init_release_rows (int): Number of lines to allow through the pipeline.
-        callback (function): The callback funciton that will be called when release is called.
+        callback (function): The callback function that will be called when release is called.
     """
 
     def __init__(self, init_release_rows, callback=None):
@@ -1710,7 +1692,7 @@ class SyncWaitDataset(DatasetOp):
         input_dataset (Dataset): Input dataset to apply flow control.
         num_batch (int): the number of batches without blocking at the start of each epoch.
         condition_name (str): The condition name that is used to toggle sending next row.
-        callback (function): The callback funciton that will be invoked when sync_update is called.
+        callback (function): The callback function that will be invoked when sync_update is called.
 
     Raises:
         RuntimeError: If condition name already exists.
@@ -2066,7 +2048,7 @@ class SkipDataset(DatasetOp):
     The result of applying Skip operator to the input Dataset.
 
     Args:
-        datasets (tuple): A tuple of datasets to be skipped.
+        input_dataset (tuple): A tuple of datasets to be skipped.
         count (int): Number of rows the dataset should be skipped.
     """
 
@@ -3055,7 +3037,7 @@ class GeneratorDataset(MappableDataset):
             provide either column_names or schema.
         column_types (list[mindspore.dtype], optional): List of column data types of the dataset (default=None).
             If provided, sanity check will be performed on generator output.
-        schema (Schema/String, optional): Path to the json schema file or schema object (default=None). Users are
+        schema (Schema/str, optional): Path to the json schema file or schema object (default=None). Users are
             required to provide either column_names or schema. If both are provided, schema will be used.
         num_samples (int, optional): The number of samples to be included in the dataset
             (default=None, all images).
@@ -4343,7 +4325,7 @@ class CelebADataset(MappableDataset):
         dataset_dir (str): Path to the root directory that contains the dataset.
         num_parallel_workers (int, optional): Number of workers to read the data (default=value set in the config).
         shuffle (bool, optional): Whether to perform shuffle on the dataset (default=None).
-        dataset_type (string): one of 'all', 'train', 'valid' or 'test'.
+        dataset_type (str): one of 'all', 'train', 'valid' or 'test'.
         sampler (Sampler, optional): Object used to choose samples from the dataset (default=None).
         decode (bool, optional): decode the images after reading (default=False).
         extensions (list[str], optional): List of file extensions to be
@@ -4874,18 +4856,15 @@ class BuildVocabDataset(DatasetOp):
     text.Vocab.from_dataset()
 
     Args:
-        vocab(Vocab): vocab object.
+        vocab(Vocab): text.vocab object.
         columns(str or list, optional): column names to get words from. It can be a list of column names (Default is
-        None, all columns are used, return error if any column isn't string).
+            None, all columns are used, return error if any column isn't string).
         freq_range(tuple, optional): A tuple of integers (min_frequency, max_frequency). Words within the frequency
-        range would be kept. 0 <= min_frequency <= max_frequency <= total_words. min_frequency/max_frequency
-        can be None, which corresponds to 0/total_words separately (default is None, all words are included).
+            range would be kept. 0 <= min_frequency <= max_frequency <= total_words. min_frequency/max_frequency
+            can be None, which corresponds to 0/total_words separately (default=None, all words are included).
         top_k(int, optional): top_k > 0. Number of words to be built into vocab. top_k most frequent words are
-        taken. The top_k is taken after freq_range. If not enough top_k, all words will be taken (default is None
-        all words are included).
-
-    Returns:
-        BuildVocabDataset
+            taken. The top_k is taken after freq_range. If not enough top_k, all words will be taken (default=None,
+            all words are included).
     """
 
     def __init__(self, input_dataset, vocab, columns, freq_range, top_k, prefetch_size=None):

mindspore/dataset/text/transforms.py

@@ -30,8 +30,8 @@ class Lookup(cde.LookupOp):
     """
         Lookup operator that looks up a word to an id
     Args:
-        vocab(Vocab): a Vocab object
-        unknown(None,int): default id to lookup a word that is out of vocab
+        vocab(Vocab): a Vocab object.
+        unknown(int): default id to lookup a word that is out of vocab (default is None).
     """
 
     @check_lookup
@@ -45,16 +45,21 @@ class Lookup(cde.LookupOp):
 class Ngram(cde.NgramOp):
     """
     TensorOp to generate n-gram from a 1-D string Tensor
-    Refer to https://en.wikipedia.org/wiki/N-gram#Examples for an explanation of what n-gram is.
+    Refer to https://en.wikipedia.org/wiki/N-gram#Examples for an overview of what n-gram is and how it works.
+
     Args:
-        n(int or list):  n in n-gram, n >= 1. n is a list of positive integers, for e.g. n=[4,3], The result
-        would be a 4-gram followed by a 3-gram in the same tensor.
-        left_pad(tuple, optional): ("pad_token",pad_width). Padding performed on left side of the sequence. pad_width
-        will be capped at n-1. left_pad=("_",2) would pad left side of the sequence with "__". (Default is None)
-        right_pad(tuple, optional): ("pad_token",pad_width). Padding performed on right side of the sequence. pad_width
-        will be capped at n-1. right_pad=("-":2) would pad right side of the sequence with "--". (Default is None)
+        n([int, list]):  n in n-gram, n >= 1. n is a list of positive integers, for e.g. n=[4,3], The result
+            would be a 4-gram followed by a 3-gram in the same tensor. If number of words is not enough to make up for
+            a n-gram, an empty string would be returned. For e.g. 3 grams on ["mindspore","best"] would result in an
+            empty string be produced.
+        left_pad(tuple, optional): ("pad_token", pad_width). Padding performed on left side of the sequence. pad_width
+            will be capped at n-1. left_pad=("_",2) would pad left side of the sequence with "__" (Default is None).
+        right_pad(tuple, optional): ("pad_token", pad_width). Padding performed on right side of the sequence.
+            pad_width will be capped at n-1. right_pad=("-":2) would pad right side of the sequence with "--"
+            (Default is None).
         separator(str,optional): symbol used to join strings together. for e.g. if 2-gram the ["mindspore", "amazing"]
-        with separator="-" the result would be ["mindspore-amazing"]. (Default is None which means whitespace is used)
+            with separator="-" the result would be ["mindspore-amazing"] (Default is None which means whitespace is
+            used).
     """
 
     @check_ngram

mindspore/dataset/text/utils.py

@@ -12,7 +12,7 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 """
-Some basic function for nlp
+Some basic function for text
 """
 from enum import IntEnum
 
@@ -25,42 +25,47 @@ from .validators import check_from_file, check_from_list, check_from_dict, check
 
 class Vocab(cde.Vocab):
     """
-        Vocab object that is used for lookup word
+        Vocab object that is used for lookup word.
     """
 
     @classmethod
     @check_from_dataset
     def from_dataset(cls, dataset, columns=None, freq_range=None, top_k=None):
         """
-        Build a vocab from a dataset. This would collect all the unique words in a dataset and return a vocab
-        which contains top_k most frequent words (if top_k is specified)
+        Build a vocab from a dataset. This would collect all unique words in a dataset and return a vocab within
+        the frequency range specified by user in freq_range. User would be warned if no words fall into the frequency.
+        Words in vocab are ordered from highest frequency to lowest frequency. Words with the same frequency would be
+        ordered lexicographically.
+
         Args:
             dataset(Dataset): dataset to build vocab from.
-            columns(str or list, optional): column names to get words from. It can be a list of column names.
-                (Default is None where all columns will be used. If any column isn't string type, will return error)
+            columns([str, list], optional): column names to get words from. It can be a list of column names.
+                (Default=None where all columns will be used. If any column isn't string type, will return error)
             freq_range(tuple, optional): A tuple of integers (min_frequency, max_frequency). Words within the frequency
-                range would be kept. 0 <= min_frequency <= max_frequency <= total_words. min_frequency/max_frequency
-                can be None, which corresponds to 0/total_words separately (default is None, all words are included)
+                range would be kept. 0 <= min_frequency <= max_frequency <= total_words. min_frequency=0 is the same as
+                min_frequency=1. max_frequency > total_words is the same as max_frequency = total_words.
+                min_frequency/max_frequency can be None, which corresponds to 0/total_words separately
+                (default=None, all words are included).
             top_k(int, optional): top_k > 0. Number of words to be built into vocab. top_k most frequent words are
-                taken. top_k is taken after freq_range. If not enough top_k, all words will be taken. (default is None
-                all words are included)
+                taken. top_k is taken after freq_range. If not enough top_k, all words will be taken. (default=None
+                all words are included).
         return:
-            text.Vocab: vocab object built from dataset.
+            text.Vocab: Vocab object built from dataset.
         """
         vocab = Vocab()
         root = copy.deepcopy(dataset).build_vocab(vocab, columns, freq_range, top_k)
         for d in root.create_dict_iterator():
             if d is not None:
-                raise ValueError("from_dataset should receive data other than None")
+                raise ValueError("from_dataset should receive data other than None.")
         return vocab
 
     @classmethod
     @check_from_list
     def from_list(cls, word_list):
         """
-           build a vocab object from a list of word
+            build a vocab object from a list of word.
         Args:
-            word_list(list): a list of string where each element is a word
+            word_list(list): a list of string where each element is a word.
         """
         return super().from_list(word_list)
 
@@ -68,11 +73,12 @@ class Vocab(cde.Vocab):
     @check_from_file
     def from_file(cls, file_path, delimiter=None, vocab_size=None):
         """
-            build a vocab object from a list of word
+            build a vocab object from a list of word.
         Args:
-            file_path(str): path to the file which contains the vocab list
-            delimiter(None, str): a delimiter to break up each line in file, the first element is taken to be the word
-            vocab_size(None, int): number of words to read from file_path
+            file_path(str): path to the file which contains the vocab list.
+            delimiter(str, optional): a delimiter to break up each line in file, the first element is taken to be
+                the word (default=None).
+            vocab_size(int, optional): number of words to read from file_path (default=None, all words are taken).
         """
         return super().from_file(file_path, delimiter, vocab_size)
 
@@ -82,7 +88,7 @@ class Vocab(cde.Vocab):
         """
             build a vocab object from a dict.
         Args:
-            word_dict(dict): dict contains word, id pairs. id should start from 2 and continuous
+            word_dict(dict): dict contains word, id pairs. id should start from 2 and be continuous.
         """
         return super().from_dict(word_dict)
 
@@ -100,7 +106,7 @@ def to_str(array, encoding='utf8'):
     """
 
     if not isinstance(array, np.ndarray):
-        raise ValueError('input should be a numpy array')
+        raise ValueError('input should be a numpy array.')
 
     return np.char.decode(array, encoding)
 
@@ -118,7 +124,7 @@ def to_bytes(array, encoding='utf8'):
     """
 
     if not isinstance(array, np.ndarray):
-        raise ValueError('input should be a numpy array')
+        raise ValueError('input should be a numpy array.')
 
     return np.char.encode(array, encoding)
 

mindspore/dataset/text/validators.py

@@ -24,7 +24,7 @@ from ..transforms.validators import check_uint32, check_pos_int64
 
 
 def check_lookup(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     @wraps(method)
     def new_method(self, *args, **kwargs):
@@ -35,10 +35,10 @@ def check_lookup(method):
             unknown = kwargs.get("unknown")
         if unknown is not None:
             if not (isinstance(unknown, int) and unknown >= 0):
-                raise ValueError("unknown needs to be a non-negative integer")
+                raise ValueError("unknown needs to be a non-negative integer.")
 
         if not isinstance(vocab, cde.Vocab):
-            raise ValueError("vocab is not an instance of cde.Vocab")
+            raise ValueError("vocab is not an instance of cde.Vocab.")
 
         kwargs["vocab"] = vocab
         kwargs["unknown"] = unknown
@@ -48,7 +48,7 @@ def check_lookup(method):
 
 
 def check_from_file(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     @wraps(method)
     def new_method(self, *args, **kwargs):
@@ -61,16 +61,16 @@ def check_from_file(method):
             vocab_size = kwargs.get("vocab_size")
 
         if not isinstance(file_path, str):
-            raise ValueError("file_path needs to be str")
+            raise ValueError("file_path needs to be str.")
 
         if delimiter is not None:
             if not isinstance(delimiter, str):
-                raise ValueError("delimiter needs to be str")
+                raise ValueError("delimiter needs to be str.")
         else:
             delimiter = ""
         if vocab_size is not None:
             if not (isinstance(vocab_size, int) and vocab_size > 0):
-                raise ValueError("vocab size needs to be a positive integer")
+                raise ValueError("vocab size needs to be a positive integer.")
         else:
             vocab_size = -1
         kwargs["file_path"] = file_path
@@ -82,7 +82,7 @@ def check_from_file(method):
 
 
 def check_from_list(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     @wraps(method)
     def new_method(self, *args, **kwargs):
@@ -90,10 +90,10 @@ def check_from_list(method):
         if "word_list" in kwargs:
             word_list = kwargs.get("word_list")
         if not isinstance(word_list, list):
-            raise ValueError("word_list needs to be a list of words")
+            raise ValueError("word_list needs to be a list of words.")
         for word in word_list:
             if not isinstance(word, str):
-                raise ValueError("each word in word list needs to be type str")
+                raise ValueError("each word in word list needs to be type str.")
 
         kwargs["word_list"] = word_list
         return method(self, **kwargs)
@@ -102,7 +102,7 @@ def check_from_list(method):
 
 
 def check_from_dict(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     @wraps(method)
     def new_method(self, *args, **kwargs):
@@ -110,12 +110,12 @@ def check_from_dict(method):
         if "word_dict" in kwargs:
             word_dict = kwargs.get("word_dict")
         if not isinstance(word_dict, dict):
-            raise ValueError("word_dict needs to be a list of word,id pairs")
+            raise ValueError("word_dict needs to be a list of word,id pairs.")
         for word, word_id in word_dict.items():
             if not isinstance(word, str):
-                raise ValueError("each word in word_dict needs to be type str")
+                raise ValueError("each word in word_dict needs to be type str.")
             if not (isinstance(word_id, int) and word_id >= 0):
-                raise ValueError("each word id needs to be positive integer")
+                raise ValueError("each word id needs to be positive integer.")
         kwargs["word_dict"] = word_dict
         return method(self, **kwargs)
 
@@ -135,11 +135,11 @@ def check_jieba_init(method):
             mp_path = kwargs.get("mp_path")
         if hmm_path is None:
             raise ValueError(
-                "the dict of HMMSegment in cppjieba is not provided")
+                "the dict of HMMSegment in cppjieba is not provided.")
         kwargs["hmm_path"] = hmm_path
         if mp_path is None:
             raise ValueError(
-                "the dict of MPSegment in cppjieba is not provided")
+                "the dict of MPSegment in cppjieba is not provided.")
         kwargs["mp_path"] = mp_path
         if model is not None:
             kwargs["model"] = model
@@ -160,7 +160,7 @@ def check_jieba_add_word(method):
         if "freq" in kwargs:
             freq = kwargs.get("freq")
         if word is None:
-            raise ValueError("word is not provided")
+            raise ValueError("word is not provided.")
         kwargs["word"] = word
         if freq is not None:
             check_uint32(freq)
@@ -179,7 +179,7 @@ def check_jieba_add_dict(method):
         if "user_dict" in kwargs:
             user_dict = kwargs.get("user_dict")
         if user_dict is None:
-            raise ValueError("user_dict is not provided")
+            raise ValueError("user_dict is not provided.")
         kwargs["user_dict"] = user_dict
         return method(self, **kwargs)
 
@@ -187,7 +187,7 @@ def check_jieba_add_dict(method):
 
 
 def check_from_dataset(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     # def from_dataset(cls, dataset, columns, freq_range=None, top_k=None):
     @wraps(method)
@@ -210,27 +210,27 @@ def check_from_dataset(method):
 
         for column in columns:
             if not isinstance(column, str):
-                raise ValueError("columns need to be a list of strings")
+                raise ValueError("columns need to be a list of strings.")
 
         if freq_range is None:
             freq_range = (None, None)
 
         if not isinstance(freq_range, tuple) or len(freq_range) != 2:
-            raise ValueError("freq_range needs to be either None or a tuple of 2 integers or an int and a None")
+            raise ValueError("freq_range needs to be either None or a tuple of 2 integers or an int and a None.")
 
         for num in freq_range:
             if num is not None and (not isinstance(num, int)):
-                raise ValueError("freq_range needs to be either None or a tuple of 2 integers or an int and a None")
+                raise ValueError("freq_range needs to be either None or a tuple of 2 integers or an int and a None.")
 
         if isinstance(freq_range[0], int) and isinstance(freq_range[1], int):
             if freq_range[0] > freq_range[1] or freq_range[0] < 0:
-                raise ValueError("frequency range [a,b] should be 0 <= a <= b (a,b are inclusive)")
+                raise ValueError("frequency range [a,b] should be 0 <= a <= b (a,b are inclusive).")
 
         if top_k is not None and (not isinstance(top_k, int)):
-            raise ValueError("top_k needs to be a positive integer")
+            raise ValueError("top_k needs to be a positive integer.")
 
         if isinstance(top_k, int) and top_k <= 0:
-            raise ValueError("top_k needs to be a positive integer")
+            raise ValueError("top_k needs to be a positive integer.")
 
         kwargs["dataset"] = dataset
         kwargs["columns"] = columns
@@ -243,7 +243,7 @@ def check_from_dataset(method):
 
 
 def check_ngram(method):
-    """A wrapper that wrap a parameter checker to the original function(crop operation)."""
+    """A wrapper that wrap a parameter checker to the original function."""
 
     @wraps(method)
     def new_method(self, *args, **kwargs):
@@ -261,11 +261,11 @@ def check_ngram(method):
             n = [n]
 
         if not (isinstance(n, list) and n != []):
-            raise ValueError("n needs to be a non-empty list of positive integers")
+            raise ValueError("n needs to be a non-empty list of positive integers.")
 
         for gram in n:
             if not (isinstance(gram, int) and gram > 0):
-                raise ValueError("n in ngram needs to be a positive number\n")
+                raise ValueError("n in ngram needs to be a positive number.")
 
         if left_pad is None:
             left_pad = ("", 0)
@@ -275,20 +275,20 @@ def check_ngram(method):
 
         if not (isinstance(left_pad, tuple) and len(left_pad) == 2 and isinstance(left_pad[0], str) and isinstance(
                 left_pad[1], int)):
-            raise ValueError("left_pad needs to be a tuple of (str, int) str is pad token and int is pad_width")
+            raise ValueError("left_pad needs to be a tuple of (str, int) str is pad token and int is pad_width.")
 
         if not (isinstance(right_pad, tuple) and len(right_pad) == 2 and isinstance(right_pad[0], str) and isinstance(
                 right_pad[1], int)):
-            raise ValueError("right_pad needs to be a tuple of (str, int) str is pad token and int is pad_width")
+            raise ValueError("right_pad needs to be a tuple of (str, int) str is pad token and int is pad_width.")
 
         if not (left_pad[1] >= 0 and right_pad[1] >= 0):
-            raise ValueError("padding width need to be positive numbers")
+            raise ValueError("padding width need to be positive numbers.")
 
         if separator is None:
             separator = " "
 
         if not isinstance(separator, str):
-            raise ValueError("separator needs to be a string")
+            raise ValueError("separator needs to be a string.")
 
         kwargs["n"] = n
         kwargs["left_pad"] = left_pad

tests/ut/python/dataset/test_ngram_op.py

@@ -16,7 +16,7 @@
 Testing Ngram in mindspore.dataset
 """
 import mindspore.dataset as ds
-import mindspore.dataset.text as nlp
+import mindspore.dataset.text as text
 import numpy as np
 
 
@@ -39,7 +39,7 @@ def test_multiple_ngrams():
             yield (np.array(line.split(" "), dtype='S'),)
 
     dataset = ds.GeneratorDataset(gen(plates_mottos), column_names=["text"])
-    dataset = dataset.map(input_columns=["text"], operations=nlp.Ngram([1, 2, 3], ("_", 2), ("_", 2), " "))
+    dataset = dataset.map(input_columns=["text"], operations=text.Ngram([1, 2, 3], ("_", 2), ("_", 2), " "))
 
     i = 0
     for data in dataset.create_dict_iterator():
@@ -61,7 +61,7 @@ def test_simple_ngram():
             yield (np.array(line.split(" "), dtype='S'),)
 
     dataset = ds.GeneratorDataset(gen(plates_mottos), column_names=["text"])
-    dataset = dataset.map(input_columns=["text"], operations=nlp.Ngram(3, separator=None))
+    dataset = dataset.map(input_columns=["text"], operations=text.Ngram(3, separator=None))
 
     i = 0
     for data in dataset.create_dict_iterator():
@@ -73,11 +73,11 @@ def test_corner_cases():
     """ testing various corner cases and exceptions"""
 
     def test_config(input_line, output_line, n, l_pad=None, r_pad=None, sep=None):
-        def gen(text):
-            yield (np.array(text.split(" "), dtype='S'),)
+        def gen(texts):
+            yield (np.array(texts.split(" "), dtype='S'),)
 
         dataset = ds.GeneratorDataset(gen(input_line), column_names=["text"])
-        dataset = dataset.map(input_columns=["text"], operations=nlp.Ngram(n, l_pad, r_pad, separator=sep))
+        dataset = dataset.map(input_columns=["text"], operations=text.Ngram(n, l_pad, r_pad, separator=sep))
         for data in dataset.create_dict_iterator():
             assert [d.decode("utf8") for d in data["text"]] == output_line, output_line