Dataframe - pandas.DataFrame.count. #. Count non-NA cells for each column or row. The values None, NaN, NaT, and optionally numpy.inf (depending on pandas.options.mode.use_inf_as_na) are considered NA. If 0 or ‘index’ counts are generated for each column. If 1 or ‘columns’ counts are generated for each row. Include only float, int or boolean data.

 
DataFrame. insert (loc, column, value, allow_duplicates = _NoDefault.no_default) [source] # Insert column into DataFrame at specified location. . Womenpercent27s ufc

pandas.DataFrame.at #. pandas.DataFrame.at. #. property DataFrame.at [source] #. Access a single value for a row/column label pair. Similar to loc, in that both provide label-based lookups. Use at if you only need to get or set a single value in a DataFrame or Series. Raises.this is a special case of adding a new column to a pandas dataframe. Here, I am adding a new feature/column based on an existing column data of the dataframe. so, let our dataFrame has columns 'feature_1', 'feature_2', 'probability_score' and we have to add a new_column 'predicted_class' based on data in column 'probability_score'.Dask DataFrame. A Dask DataFrame is a large parallel DataFrame composed of many smaller pandas DataFrames, split along the index. These pandas DataFrames may live on disk for larger-than-memory computing on a single machine, or on many different machines in a cluster. One Dask DataFrame operation triggers many operations on the constituent ... Pandas where () method is used to check a data frame for one or more condition and return the result accordingly. By default, The rows not satisfying the condition are filled with NaN value. Syntax: DataFrame.where (cond, other=nan, inplace=False, axis=None, level=None, errors=’raise’, try_cast=False, raise_on_error=None)this is a special case of adding a new column to a pandas dataframe. Here, I am adding a new feature/column based on an existing column data of the dataframe. so, let our dataFrame has columns 'feature_1', 'feature_2', 'probability_score' and we have to add a new_column 'predicted_class' based on data in column 'probability_score'.1, or ‘columns’ : Drop columns which contain missing value. Only a single axis is allowed. how{‘any’, ‘all’}, default ‘any’. Determine if row or column is removed from DataFrame, when we have at least one NA or all NA. ‘any’ : If any NA values are present, drop that row or column. ‘all’ : If all values are NA, drop that ...Jun 22, 2021 · A Dataframe is a two-dimensional data structure, i.e., data is aligned in a tabular fashion in rows and columns. In dataframe datasets arrange in rows and columns, we can store any number of datasets in a dataframe. We can perform many operations on these datasets like arithmetic operation, columns/rows selection, columns/rows addition etc. DataFrame.apply(func, axis=0, raw=False, result_type=None, args=(), by_row='compat', **kwargs) [source] #. Apply a function along an axis of the DataFrame. Objects passed to the function are Series objects whose index is either the DataFrame’s index ( axis=0) or the DataFrame’s columns ( axis=1 ). By default ( result_type=None ), the final ...class pandas.DataFrame(data=None, index=None, columns=None, dtype=None, copy=None) [source] #. Two-dimensional, size-mutable, potentially heterogeneous tabular data. Data structure also contains labeled axes (rows and columns). Arithmetic operations align on both row and column labels. Can be thought of as a dict-like container for Series objects. The StructType and StructFields are used to define a schema or its part for the Dataframe. This defines the name, datatype, and nullable flag for each column. StructType object is the collection of StructFields objects. It is a Built-in datatype that contains the list of StructField.Let’s discuss how to get column names in Pandas dataframe. First, let’s create a simple dataframe with nba.csv file. Now let’s try to get the columns name from above dataset. Method #3: Using keys () function: It will also give the columns of the dataframe. Method #4: column.values method returns an array of index.Jun 22, 2021 · A Dataframe is a two-dimensional data structure, i.e., data is aligned in a tabular fashion in rows and columns. In dataframe datasets arrange in rows and columns, we can store any number of datasets in a dataframe. We can perform many operations on these datasets like arithmetic operation, columns/rows selection, columns/rows addition etc. property DataFrame.loc [source] #. Access a group of rows and columns by label (s) or a boolean array. .loc [] is primarily label based, but may also be used with a boolean array. Allowed inputs are: A single label, e.g. 5 or 'a', (note that 5 is interpreted as a label of the index, and never as an integer position along the index).Construct DataFrame from dict of array-like or dicts. Creates DataFrame object from dictionary by columns or by index allowing dtype specification. Of the form {field : array-like} or {field : dict}. The “orientation” of the data. If the keys of the passed dict should be the columns of the resulting DataFrame, pass ‘columns’ (default).Dicts can be used to specify different replacement values for different existing values. For example, {'a': 'b', 'y': 'z'} replaces the value ‘a’ with ‘b’ and ‘y’ with ‘z’. To use a dict in this way, the optional value parameter should not be given. For a DataFrame a dict can specify that different values should be replaced in ...Dicts can be used to specify different replacement values for different existing values. For example, {'a': 'b', 'y': 'z'} replaces the value ‘a’ with ‘b’ and ‘y’ with ‘z’. To use a dict in this way, the optional value parameter should not be given. For a DataFrame a dict can specify that different values should be replaced in ...The DataFrame and DataFrameColumn classes expose a number of useful APIs: binary operations, computations, joins, merges, handling missing values and more. Let’s look at some of them: // Add 5 to Ints through the DataFrame df["Ints"].Add(5, inPlace: true); // We can also use binary operators.pandas.DataFrame.at# property DataFrame. at [source] #. Access a single value for a row/column label pair. Similar to loc, in that both provide label-based lookups.Use at if you only need to get or set a single value in a DataFrame or Series. Construct DataFrame from dict of array-like or dicts. Creates DataFrame object from dictionary by columns or by index allowing dtype specification. Of the form {field : array-like} or {field : dict}. The “orientation” of the data. If the keys of the passed dict should be the columns of the resulting DataFrame, pass ‘columns’ (default).A bar plot is a plot that presents categorical data with rectangular bars with lengths proportional to the values that they represent. A bar plot shows comparisons among discrete categories. One axis of the plot shows the specific categories being compared, and the other axis represents a measured value. Parameters. xlabel or position, optional.Mar 7, 2022 · Add a Row to a Pandas DataFrame. The easiest way to add or insert a new row into a Pandas DataFrame is to use the Pandas .concat () function. To learn more about how these functions work, check out my in-depth article here. In this section, you’ll learn three different ways to add a single row to a Pandas DataFrame. Let’s discuss how to get column names in Pandas dataframe. First, let’s create a simple dataframe with nba.csv file. Now let’s try to get the columns name from above dataset. Method #3: Using keys () function: It will also give the columns of the dataframe. Method #4: column.values method returns an array of index.property DataFrame.loc [source] #. Access a group of rows and columns by label (s) or a boolean array. .loc [] is primarily label based, but may also be used with a boolean array. Allowed inputs are: A single label, e.g. 5 or 'a', (note that 5 is interpreted as a label of the index, and never as an integer position along the index). pandas.DataFrame.at #. pandas.DataFrame.at. #. property DataFrame.at [source] #. Access a single value for a row/column label pair. Similar to loc, in that both provide label-based lookups. Use at if you only need to get or set a single value in a DataFrame or Series. Raises.Dec 16, 2019 · DataFrame df = new DataFrame(dateTimes, ints, strings); // This will throw if the columns are of different lengths One of the benefits of using a notebook for data exploration is the interactive REPL. We can enter df into a new cell and run it to see what data it contains. For the rest of this post, we’ll work in a .NET Jupyter environment. pd.DataFrame is expecting a dictionary with list values, but you are feeding an irregular combination of list and dictionary values.. Your desired output is distracting, because it does not conform to a regular MultiIndex, which should avoid empty strings as labels for the first level.Jan 4, 2019 · pd.DataFrame is expecting a dictionary with list values, but you are feeding an irregular combination of list and dictionary values.. Your desired output is distracting, because it does not conform to a regular MultiIndex, which should avoid empty strings as labels for the first level. Jul 31, 2015 · In many situations, a custom attribute attached to a pd.DataFrame object is not necessary. In addition, note that pandas-object attributes may not serialize. So pickling will lose this data. Instead, consider creating a dictionary with appropriately named keys and access the dataframe via dfs['some_label']. df = pd.DataFrame() dfs = {'some ... Dicts can be used to specify different replacement values for different existing values. For example, {'a': 'b', 'y': 'z'} replaces the value ‘a’ with ‘b’ and ‘y’ with ‘z’. To use a dict in this way, the optional value parameter should not be given. For a DataFrame a dict can specify that different values should be replaced in ...Apply a function to a Dataframe elementwise. Deprecated since version 2.1.0: DataFrame.applymap has been deprecated. Use DataFrame.map instead. This method applies a function that accepts and returns a scalar to every element of a DataFrame. Python function, returns a single value from a single value. If ‘ignore’, propagate NaN values ... A Dask DataFrame is a large parallel DataFrame composed of many smaller pandas DataFrames, split along the index. These pandas DataFrames may live on disk for larger-than-memory computing on a single machine, or on many different machines in a cluster. One Dask DataFrame operation triggers many operations on the constituent pandas DataFrames.A DataFrame with mixed type columns(e.g., str/object, int64, float32) results in an ndarray of the broadest type that accommodates these mixed types (e.g., object). To read the multi-line JSON as a DataFrame: val spark = SparkSession.builder().getOrCreate() val df = spark.read.json(spark.sparkContext.wholeTextFiles("file.json").values) Reading large files in this manner is not recommended, from the wholeTextFiles docs. Small files are preferred, large file is also allowable, but may cause bad performance.DataFrame.sort_values(by, *, axis=0, ascending=True, inplace=False, kind='quicksort', na_position='last', ignore_index=False, key=None) [source] #. Sort by the values along either axis. Name or list of names to sort by. if axis is 0 or ‘index’ then by may contain index levels and/or column labels. if axis is 1 or ‘columns’ then by may ... Feb 20, 2019 · Python | Pandas DataFrame.columns. Pandas DataFrame is a two-dimensional size-mutable, potentially heterogeneous tabular data structure with labeled axes (rows and columns). Arithmetic operations align on both row and column labels. It can be thought of as a dict-like container for Series objects. This is the primary data structure of the Pandas. The StructType and StructFields are used to define a schema or its part for the Dataframe. This defines the name, datatype, and nullable flag for each column. StructType object is the collection of StructFields objects. It is a Built-in datatype that contains the list of StructField.Pandas where () method is used to check a data frame for one or more condition and return the result accordingly. By default, The rows not satisfying the condition are filled with NaN value. Syntax: DataFrame.where (cond, other=nan, inplace=False, axis=None, level=None, errors=’raise’, try_cast=False, raise_on_error=None)Jan 31, 2022 · Method 1 — Pivoting. This transformation is essentially taking a longer-format DataFrame and making it broader. Often this is a result of having a unique identifier repeated along multiple rows for each subsequent entry. One method to derive a newly formatted DataFrame is by using DataFrame.pivot. Saving a DataFrame to a Python dictionary dictionary = df.to_dict() Saving a DataFrame to a Python string string = df.to_string() Note: sometimes may be useful for debugging Working with the whole DataFrame Peek at the DataFrame contents df.info() # index & data types n = 4 dfh = df.head(n) # get first n rows DataFrame.mask(cond, other=_NoDefault.no_default, *, inplace=False, axis=None, level=None) [source] #. Replace values where the condition is True. Where cond is False, keep the original value. Where True, replace with corresponding value from other . If cond is callable, it is computed on the Series/DataFrame and should return boolean Series ... Create a data frame using the function pd.DataFrame () The data frame contains 3 columns and 5 rows. Print the data frame output with the print () function. We write pd. in front of DataFrame () to let Python know that we want to activate the DataFrame () function from the Pandas library. Be aware of the capital D and F in DataFrame! Dask DataFrame. A Dask DataFrame is a large parallel DataFrame composed of many smaller pandas DataFrames, split along the index. These pandas DataFrames may live on disk for larger-than-memory computing on a single machine, or on many different machines in a cluster. One Dask DataFrame operation triggers many operations on the constituent ... Jul 31, 2015 · In many situations, a custom attribute attached to a pd.DataFrame object is not necessary. In addition, note that pandas-object attributes may not serialize. So pickling will lose this data. Instead, consider creating a dictionary with appropriately named keys and access the dataframe via dfs['some_label']. df = pd.DataFrame() dfs = {'some ... Feb 20, 2019 · Python | Pandas DataFrame.columns. Pandas DataFrame is a two-dimensional size-mutable, potentially heterogeneous tabular data structure with labeled axes (rows and columns). Arithmetic operations align on both row and column labels. It can be thought of as a dict-like container for Series objects. This is the primary data structure of the Pandas. DataFrame Creation¶ A PySpark DataFrame can be created via pyspark.sql.SparkSession.createDataFrame typically by passing a list of lists, tuples, dictionaries and pyspark.sql.Row s, a pandas DataFrame and an RDD consisting of such a list. pyspark.sql.SparkSession.createDataFrame takes the schema argument to specify the schema of the DataFrame ... df_copy = df.copy() # copy into a new dataframe object df_copy = df # make an alias of the dataframe(not creating # a new dataframe, just a pointer) Note : The two methods shown above are different — the copy() function creates a totally new dataframe object independent of the original one while the variable copy method just creates an alias ...So you can use the isnull ().sum () function instead. This returns a summary of all missing values for each column: DataFrame.isnull () .sum () 6. Dataframe.info. The info () function is an essential pandas operation. It returns the summary of non-missing values for each column instead: DataFrame.info () 7.Dec 16, 2019 · DataFrame df = new DataFrame(dateTimes, ints, strings); // This will throw if the columns are of different lengths One of the benefits of using a notebook for data exploration is the interactive REPL. We can enter df into a new cell and run it to see what data it contains. For the rest of this post, we’ll work in a .NET Jupyter environment. Dec 16, 2019 · DataFrame df = new DataFrame(dateTimes, ints, strings); // This will throw if the columns are of different lengths One of the benefits of using a notebook for data exploration is the interactive REPL. We can enter df into a new cell and run it to see what data it contains. For the rest of this post, we’ll work in a .NET Jupyter environment. Returns a new DataFrame using the row indices in rowIndices. Filter(PrimitiveDataFrameColumn<Int64>) Returns a new DataFrame using the row indices in rowIndices. FromArrowRecordBatch(RecordBatch) Wraps a DataFrame around an Arrow Apache.Arrow.RecordBatch without copying data. GroupBy(String) Returns a new DataFrame using the row indices in rowIndices. Filter(PrimitiveDataFrameColumn<Int64>) Returns a new DataFrame using the row indices in rowIndices. FromArrowRecordBatch(RecordBatch) Wraps a DataFrame around an Arrow Apache.Arrow.RecordBatch without copying data. GroupBy(String)Merge DataFrame or named Series objects with a database-style join. A named Series object is treated as a DataFrame with a single named column. The join is done on columns or indexes. If joining columns on columns, the DataFrame indexes will be ignored. Otherwise if joining indexes on indexes or indexes on a column or columns, the index will be ...A Pandas DataFrame is a 2 dimensional data structure, like a 2 dimensional array, or a table with rows and columns. Example Get your own Python Server Create a simple Pandas DataFrame: import pandas as pd data = { "calories": [420, 380, 390], "duration": [50, 40, 45] } #load data into a DataFrame object: df = pd.DataFrame (data) print(df) ResultDataFrame.index #. The index (row labels) of the DataFrame. The index of a DataFrame is a series of labels that identify each row. The labels can be integers, strings, or any other hashable type. The index is used for label-based access and alignment, and can be accessed or modified using this attribute. pandas.DataFrame.dtypes #. pandas.DataFrame.dtypes. #. Return the dtypes in the DataFrame. This returns a Series with the data type of each column. The result’s index is the original DataFrame’s columns. Columns with mixed types are stored with the object dtype. See the User Guide for more. DataFrame.sort_values(by, *, axis=0, ascending=True, inplace=False, kind='quicksort', na_position='last', ignore_index=False, key=None) [source] #. Sort by the values along either axis. Name or list of names to sort by. if axis is 0 or ‘index’ then by may contain index levels and/or column labels. if axis is 1 or ‘columns’ then by may ... pandas.DataFrame.dtypes #. pandas.DataFrame.dtypes. #. Return the dtypes in the DataFrame. This returns a Series with the data type of each column. The result’s index is the original DataFrame’s columns. Columns with mixed types are stored with the object dtype. See the User Guide for more. A bar plot is a plot that presents categorical data with rectangular bars with lengths proportional to the values that they represent. A bar plot shows comparisons among discrete categories. One axis of the plot shows the specific categories being compared, and the other axis represents a measured value. Parameters. xlabel or position, optional. pandas.DataFrame.columns# DataFrame. columns # The column labels of the DataFrame. Examples >>> df = pd.Sep 17, 2018 · Pandas where () method is used to check a data frame for one or more condition and return the result accordingly. By default, The rows not satisfying the condition are filled with NaN value. Syntax: DataFrame.where (cond, other=nan, inplace=False, axis=None, level=None, errors=’raise’, try_cast=False, raise_on_error=None) DataFrame.mask(cond, other=_NoDefault.no_default, *, inplace=False, axis=None, level=None) [source] #. Replace values where the condition is True. Where cond is False, keep the original value. Where True, replace with corresponding value from other . If cond is callable, it is computed on the Series/DataFrame and should return boolean Series ...pandas.DataFrame.count. #. Count non-NA cells for each column or row. The values None, NaN, NaT, and optionally numpy.inf (depending on pandas.options.mode.use_inf_as_na) are considered NA. If 0 or ‘index’ counts are generated for each column. If 1 or ‘columns’ counts are generated for each row. Include only float, int or boolean data.pd.DataFrame.query is a very elegant/intuitive way to perform this task, but is often slower. However, if you pay attention to the timings below, for large data, the ...DataFrame.apply(func, axis=0, raw=False, result_type=None, args=(), by_row='compat', **kwargs) [source] #. Apply a function along an axis of the DataFrame. Objects passed to the function are Series objects whose index is either the DataFrame’s index ( axis=0) or the DataFrame’s columns ( axis=1 ). By default ( result_type=None ), the final ...property DataFrame.loc [source] #. Access a group of rows and columns by label (s) or a boolean array. .loc [] is primarily label based, but may also be used with a boolean array. Allowed inputs are: A single label, e.g. 5 or 'a', (note that 5 is interpreted as a label of the index, and never as an integer position along the index).DataFrame.apply(func, axis=0, raw=False, result_type=None, args=(), by_row='compat', **kwargs) [source] #. Apply a function along an axis of the DataFrame. Objects passed to the function are Series objects whose index is either the DataFrame’s index ( axis=0) or the DataFrame’s columns ( axis=1 ). By default ( result_type=None ), the final ...labels for the Series and DataFrame objects. It can only contain hashable objects. A pandas Series has one Index; and a DataFrame has two Indexes. # --- get Index from Series and DataFrame idx = s.index idx = df.columns # the column index idx = df.index # the row index # --- Notesome Index attributes b = idx.is_monotonic_decreasingReturns a new DataFrame containing union of rows in this and another DataFrame. unpersist ([blocking]) Marks the DataFrame as non-persistent, and remove all blocks for it from memory and disk. unpivot (ids, values, variableColumnName, …) Unpivot a DataFrame from wide format to long format, optionally leaving identifier columns set. where ...Jul 31, 2015 · In many situations, a custom attribute attached to a pd.DataFrame object is not necessary. In addition, note that pandas-object attributes may not serialize. So pickling will lose this data. Instead, consider creating a dictionary with appropriately named keys and access the dataframe via dfs['some_label']. df = pd.DataFrame() dfs = {'some ... DataFrame. insert (loc, column, value, allow_duplicates = _NoDefault.no_default) [source] # Insert column into DataFrame at specified location. Mar 7, 2022 · Add a Row to a Pandas DataFrame. The easiest way to add or insert a new row into a Pandas DataFrame is to use the Pandas .concat () function. To learn more about how these functions work, check out my in-depth article here. In this section, you’ll learn three different ways to add a single row to a Pandas DataFrame. pandas.DataFrame.dtypes #. pandas.DataFrame.dtypes. #. Return the dtypes in the DataFrame. This returns a Series with the data type of each column. The result’s index is the original DataFrame’s columns. Columns with mixed types are stored with the object dtype. See the User Guide for more.1, or ‘columns’ : Drop columns which contain missing value. Only a single axis is allowed. how{‘any’, ‘all’}, default ‘any’. Determine if row or column is removed from DataFrame, when we have at least one NA or all NA. ‘any’ : If any NA values are present, drop that row or column. ‘all’ : If all values are NA, drop that ...A Data frame is a two-dimensional data structure, i.e., data is aligned in a tabular fashion in rows and columns. Features of DataFrame Potentially columns are of different types Size – Mutable Labeled axes (rows and columns) Can Perform Arithmetic operations on rows and columns StructureFeb 19, 2021 · Python | Pandas dataframe.add () Python is a great language for doing data analysis, primarily because of the fantastic ecosystem of data-centric Python packages. Pandas is one of those packages and makes importing and analyzing data much easier. Dataframe.add () method is used for addition of dataframe and other, element-wise (binary operator ... DataFrame.set_index(keys, *, drop=True, append=False, inplace=False, verify_integrity=False) [source] #. Set the DataFrame index using existing columns. Set the DataFrame index (row labels) using one or more existing columns or arrays (of the correct length). The index can replace the existing index or expand on it. This parameter can be either ...

Jan 31, 2022 · Method 1 — Pivoting. This transformation is essentially taking a longer-format DataFrame and making it broader. Often this is a result of having a unique identifier repeated along multiple rows for each subsequent entry. One method to derive a newly formatted DataFrame is by using DataFrame.pivot. . Applbee

dataframe

1, or ‘columns’ : Drop columns which contain missing value. Only a single axis is allowed. how{‘any’, ‘all’}, default ‘any’. Determine if row or column is removed from DataFrame, when we have at least one NA or all NA. ‘any’ : If any NA values are present, drop that row or column. ‘all’ : If all values are NA, drop that ...A Dask DataFrame is a large parallel DataFrame composed of many smaller pandas DataFrames, split along the index. These pandas DataFrames may live on disk for larger-than-memory computing on a single machine, or on many different machines in a cluster. One Dask DataFrame operation triggers many operations on the constituent pandas DataFrames.Pandas where () method is used to check a data frame for one or more condition and return the result accordingly. By default, The rows not satisfying the condition are filled with NaN value. Syntax: DataFrame.where (cond, other=nan, inplace=False, axis=None, level=None, errors=’raise’, try_cast=False, raise_on_error=None)class pandas.DataFrame(data=None, index=None, columns=None, dtype=None, copy=None) [source] #. Two-dimensional, size-mutable, potentially heterogeneous tabular data. Data structure also contains labeled axes (rows and columns). Arithmetic operations align on both row and column labels. Can be thought of as a dict-like container for Series objects. The DataFrame.index and DataFrame.columns attributes of the DataFrame instance are placed in the query namespace by default, which allows you to treat both the index and columns of the frame as a column in the frame. The identifier index is used for the frame index; you can also use the name of the index to identify it in a query.df_copy = df.copy() # copy into a new dataframe object df_copy = df # make an alias of the dataframe(not creating # a new dataframe, just a pointer) Note : The two methods shown above are different — the copy() function creates a totally new dataframe object independent of the original one while the variable copy method just creates an alias ...Dicts can be used to specify different replacement values for different existing values. For example, {'a': 'b', 'y': 'z'} replaces the value ‘a’ with ‘b’ and ‘y’ with ‘z’. To use a dict in this way, the optional value parameter should not be given. For a DataFrame a dict can specify that different values should be replaced in ...In this example the core dataframe is first formulated. pd.dataframe () is used for formulating the dataframe. Every row of the dataframe are inserted along with their column names. Once the dataframe is completely formulated it is printed on to the console. A typical float dataset is used in this instance.Since values are sorted, it is ok to take the first lines for each case. targets = df.groupby (level='case').first () * 0.926 print (targets) 1 2 3 case 1014 18.75150 26.95586 20.38126 1015 18.72372 27.05772 20.19606 1016 20.14050 27.01142 20.20532. Now, How could I simply build the following dataframe, which shows time t at wich each object ...axis {0 or ‘index’} for Series, {0 or ‘index’, 1 or ‘columns’} for DataFrame. Axis along which to fill missing values. For Series this parameter is unused and defaults to 0. inplace bool, default False. If True, fill in-place. Note: this will modify any other views on this object (e.g., a no-copy slice for a column in a DataFrame).Marks the DataFrame as non-persistent, and remove all blocks for it from memory and disk. where (condition) where() is an alias for filter(). withColumn (colName, col) Returns a new DataFrame by adding a column or replacing the existing column that has the same name. withColumnRenamed (existing, new) Returns a new DataFrame by renaming an ... Pandas 数据结构 - DataFrame. DataFrame 是一个表格型的数据结构，它含有一组有序的列，每列可以是不同的值类型（数值、字符串、布尔型值）。DataFrame 既有行索引也有列索引，它可以被看做由 Series 组成的字典（共同用一个索引）。 DataFrame 构造方法如下：.

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