Python中的Prettytable模块

Python中的Prettytable模块

在本教程中,我们将学习使用Python的Prettytable模块创建关系表。我们将在不使用外部库的情况下创建表格。

什么是Pretty Table

Pretty Table是数据在表格形式下的可视化表示。这些是ASCII表格,易于使用。prettytable库由 PrettyTable 类组成,用于创建关系表。要使用此库,我们需要使用以下命令进行安装。

安装

pip install prettytable

使用Pretty Table创建表格

在这里,我们将使用pretty table模块来创建按行排列的表格。让我们看一下以下示例。

示例1:按行创建表格

from prettytable import PrettyTable

# Creating a new table 
newTable = PrettyTable(["Student Name", "Class", "Subject", "Makrs"])

# Add rows
newTable.add_row(["Camron", "X", "English", "91"])
newTable.add_row(["Haris", "X", "Math", "63"])
newTable.add_row(["Jenny", "X", "Science", "90"])
newTable.add_row(["Bernald", "X", "Art", "92"])
newTable.add_row(["Jackson", "X", "Science", "98"])
newTable.add_row(["Samual", "X", "English", "88"])
newTable.add_row(["Stark", "X", "English", "95"])

print(newTable)

输出

+--------------+-------+---------+-------+
| Student Name | Class | Subject | Makrs |
+--------------+-------+---------+-------+
|    Camron    |   X   | English |   91  |
|    Haris     |   X   |   Math  |   63  |
|    Jenny     |   X   | Science |   90  |
|   Bernald    |   X   |   Art   |   92  |
|   Jackson    |   X   | Science |   98  |
|    Samual    |   X   | English |   88  |
|    Stark     |   X   | English |   95  |
+--------------+-------+---------+-------+

示例2:按列排列的表格

from prettytable import PrettyTable

columns = ["Student Name", "Class", "Subject", "Marks"]

newTable = PrettyTable()

# Add Columns
newTable.add_column(columns[0], ["Jacob", "Peter", "Grenger",
                    "Stark", "Falcon", "Matthew", "Jackson"])
newTable.add_column(columns[1], ["X", "X", "X", "X", "X", "X", "X"])
newTable.add_column(columns[2], ["English", "Art", "Science", "Math", "Science", "English", "English"])
newTable.add_column(columns[3], ["91", "63", "90", "92",
                                        "98", "83", "95"])

print(newTable)

输出

+--------------+-------+---------+-------------------+
| Student Name | Class | Subject | Marks |
+--------------+-------+---------+-------------------+
|    Jacob             |   X     | English |   91    |
|    Peter             |   X     |   Art   |   63    |
|   Grenger            |   X     | Science |   90    |
|    Stark             |   X     |   Math  |   92    |
|    Falcon            |   X     | Science |   98    |
|   Matthew            |   X     | English |   83    |
|   Jackson            |   X     | English |   95    |
+--------------+-------+---------+------------------+

我们使用了pretty table模块中的add_column()方法。

示例2:一次添加多行

from prettytable import PrettyTable

# Creating a new table
newTable = PrettyTable(["Student Name", "Class", "Subject", "Makrs"])

# # Add rows
newTable.add_rows( 
    [
        ["Camron", "X", "English", "91"],
        ["Haris", "X", "Math", "63"],
        ["Jenny", "X", "Science", "90"],
        ["Bernald", "X", "Art", "92"],
        ["Jackson", "X", "Science", "98"],
        ["Samual", "X", "English", "88"],
        ["Stark", "X", "English", "95"],

    ]
)

print(newTable)

输出

+--------------+-------+---------+-------+
|    Camron    |   X   | English |   91  |
|    Haris     |   X   |   Math  |   63  |
|    Jenny     |   X   | Science |   90  |
|   Bernald    |   X   |   Art   |   92  |
|   Jackson    |   X   | Science |   98  |
|    Samual    |   X   | English |   88  |
|    Stark     |   X   | English |   95  |
+--------------+-------+---------+-------+

PrettyTable 删除行

该模块提供了del_row()方法,允许我们删除行。它接受要删除的索引值并删除行。索引从零开始。让我们来了解以下代码。

示例

from prettytable import PrettyTable

# Creating a new table
newTable = PrettyTable(["Student Name", "Class", "Subject", "Makrs"])

# # Add rows
newTable.add_row(["Camron", "X", "English", "91"])
newTable.add_row(["Haris", "X", "Math", "63"])
newTable.add_row(["Jenny", "X", "Science", "90"])
newTable.add_row(["Bernald", "X", "Art", "92"])
newTable.add_row(["Jackson", "X", "Science", "98"])
newTable.add_row(["Samual", "X", "English", "88"])
newTable.add_row(["Stark", "X", "English", "95"])

newTable.del_row(1)
newTable.del_row(2)
newTable.del_row(3)

print(newTable)

输出

+--------------+-------+---------+-------+
| Student Name | Class | Subject | Makrs |
+--------------+-------+---------+-------+
|    Camron          |   X   | English |   91   |
|    Jenny               |   X   | Science |   90  |
|   Jackson            |   X   | Science |   98  |
|    Stark                |   X   | English |   95  |
+--------------+-------+---------+-------+

它将从表中删除特定的行。要清除整个表,我们使用以下方法。

myTable.clear_rows()

示例2

from prettytable import PrettyTable

# Creating a new table
newTable = PrettyTable(["Student Name", "Class", "Subject", "Makrs"])

# # Add rows
newTable.add_row(["Camron", "X", "English", "91"])
newTable.add_row(["Haris", "X", "Math", "63"])
newTable.add_row(["Jenny", "X", "Science", "90"])
newTable.add_row(["Bernald", "X", "Art", "92"])
newTable.add_row(["Jackson", "X", "Science", "98"])
newTable.add_row(["Samual", "X", "English", "88"])
newTable.add_row(["Stark", "X", "English", "95"])

newTable.clear_rows()

print(newTable)

输出

+--------------+-------+---------+------------------+
| Student Name | Class | Subject | Makrs |
+--------------+-------+---------+--------------------+
+--------------+-------+---------+--------------------+

如上所示的代码,所有行都已被删除。我们只能看到列名。

获取特定行和列

prettytable 的主要目的是以ASCII形式获取表格。我们可以使用以下方法限制表格的输出。

get_string(fields=["Column 1", "Column2", .............., ColumnN]

让我们来理解以下示例。

示例:

from prettytable import PrettyTable

# Creating a new table
newTable = PrettyTable(["Student Name", "Class", "Subject", "Makrs"])

# # Add rows
newTable.add_rows( 
    [
        ["Camron", "X", "English", "91"],
        ["Haris", "X", "Math", "63"],
        ["Jenny", "X", "Science", "90"],
        ["Bernald", "X", "Art", "92"],
        ["Jackson", "X", "Science", "98"],
        ["Samual", "X", "English", "88"],
        ["Stark", "X", "English", "95"],

    ]
)

print(newTable.get_string(fields=["Student Name", "Class"]))

输出

+--------------+--------------+
| Student Name | Class |
+--------------+--------------+
|    Camron          |   X   |
|    Haris               |   X   |
|    Jenny               |   X   |
|   Bernald            |   X   |
|   Jackson            |   X   |
|    Samual            |   X   |
|    Stark                |   X   |
+--------------+---------------+

字段参数采用要打印的字段名列表。

我们还可以使用以下方法来控制结果。

print(newTable.get_string(start=1, end=4)

输出

+--------------+-------+---------+-------------------+
| Student Name | Class | Subject | Makrs |
+--------------+-------+---------+-------------------+
|    Camron          |   X   | English |   91  |
|    Haris               |   X   |   Math  |   63  |
|    Jenny             |   X   | Science |   90  |
+--------------+-------+---------+------------------+

改变列的对齐方式

我们可以观察到表格中的所有列都居中对齐。根据需要,我们可以通过为属性 align 分配一个字符来进行更改。分别有三个字符串 – ‘l’(代表左对齐),’r’(代表右对齐)和’c’(代表居中对齐)。

让我们看下面的示例。

示例

newTable.align = 'r'
print(newTable)

输出

+--------------+-------+---------+-------------------+
| Student Name | Class | Subject | Makrs |
+--------------+-------+---------+------------------+
|           Camron |     X | English |    91  |
|             Haris  |     X |    Math |    63 |
|             Jenny |     X | Science |    90 |
|            Bernald |     X |     Art |    92 |
|           Jackson |     X | Science |    98 |
|           Samual  |     X | English |    88 |
|            Stark     |     X | English |    95 |
+--------------+-------+---------+------------------+

修改表格的外观

默认表格看起来像一个SQL数据库外壳。然而,我们可以以其他格式修改表格的外观。漂亮的表格模块提供了set_style()方法,将表格转化为适合MSWord的友好格式。

让我们看下面的示例。

示例在创建表格的代码中添加下面的代码。

from prettytable import MSWORD_FRIENDLY

newTable.set_style(MSWORD_FRIENDLY)
print(newTable)

输出

| Student Name | Class | Subject | Makrs |
|    Camron         |   X   | English   |       91  |
|    Haris              |   X   |   Math     |   63  |
|    Jenny              |   X   | Science   |   90  |
|   Bernald           |   X   |   Art         |   92  |
|   Jackson           |   X   | Science   |   98  |
|    Samual           |   X   | English   |   88  |
|    Stark               |   X   | English   |   95  |

我们可以清楚地看到默认表格和MS Word友好表格之间的区别。

结论

我们讨论了使用 prettytable 模块在表格中进行一些重要操作。这是使用Python脚本处理表格非常有效的模块。

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