Leopards with different file types

Introduction

This article covers how to use leopards with different file types.

CSV

DictReader from csv module can be used to read csv files as dictionaries as shown below.

<span>import</span> <span>csv</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>
<span>data</span> <span>=</span> <span>csv</span><span>.</span><span>DictReader</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.csv</span><span>"</span><span>))</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
<span>import</span> <span>csv</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>

<span>data</span> <span>=</span> <span>csv</span><span>.</span><span>DictReader</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.csv</span><span>"</span><span>))</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
import csv
from leopards import Q

data = csv.DictReader(open("data.csv"))
res = Q(data, {"age__gt": 15})

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TSV

DictReader from csv module can be used to read tsv files as dictionaries as shown below.

<span>import</span> <span>csv</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>
<span>data</span> <span>=</span> <span>csv</span><span>.</span><span>DictReader</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.csv</span><span>"</span><span>),</span> <span>delimiter</span><span>=</span><span>"</span><span>\t</span><span>"</span><span>)</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
<span>import</span> <span>csv</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>

<span>data</span> <span>=</span> <span>csv</span><span>.</span><span>DictReader</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.csv</span><span>"</span><span>),</span> <span>delimiter</span><span>=</span><span>"</span><span>\t</span><span>"</span><span>)</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
import csv
from leopards import Q

data = csv.DictReader(open("data.csv"), delimiter="\t")
res = Q(data, {"age__gt": 15})

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JSON

json.load can be used to read json files as dictionaries as shown below.

<span>import</span> <span>json</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>
<span>data</span> <span>=</span> <span>json</span><span>.</span><span>load</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.json</span><span>"</span><span>))</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
<span>import</span> <span>json</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>

<span>data</span> <span>=</span> <span>json</span><span>.</span><span>load</span><span>(</span><span>open</span><span>(</span><span>"</span><span>data.json</span><span>"</span><span>))</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>

import json
from leopards import Q

data = json.load(open("data.json"))
res = Q(data, {"age__gt": 15})

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XLS

xlrd library can be used to read xls files as dictionaries as shown below.

<span>import</span> <span>xlrd</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>
<span>wb</span> <span>=</span> <span>xlrd</span><span>.</span><span>open_workbook</span><span>(</span><span>"</span><span>data.xls</span><span>"</span><span>)</span>
<span>sh</span> <span>=</span> <span>wb</span><span>.</span><span>sheets</span><span>()[</span><span>0</span><span>]</span>
<span>keys</span> <span>=</span> <span>sh</span><span>.</span><span>row_values</span><span>(</span><span>0</span><span>)</span>
<span>data</span> <span>=</span><span>[]</span>
<span>for</span> <span>n</span> <span>in</span> <span>range</span><span>(</span><span>1</span><span>,</span> <span>sh</span><span>.</span><span>nrows</span><span>):</span>
    <span>data</span><span>.</span><span>append</span><span>({</span><span>key</span><span>:</span> <span>sh</span><span>.</span><span>row_values</span><span>(</span><span>n</span><span>)[</span><span>n2</span><span>]</span> <span>for</span> <span>n2</span><span>,</span> <span>key</span> <span>in</span> <span>enumerate</span><span>(</span><span>keys</span><span>)})</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>                
<span>import</span> <span>xlrd</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>

<span>wb</span> <span>=</span> <span>xlrd</span><span>.</span><span>open_workbook</span><span>(</span><span>"</span><span>data.xls</span><span>"</span><span>)</span>
<span>sh</span> <span>=</span> <span>wb</span><span>.</span><span>sheets</span><span>()[</span><span>0</span><span>]</span>
<span>keys</span> <span>=</span> <span>sh</span><span>.</span><span>row_values</span><span>(</span><span>0</span><span>)</span>
<span>data</span> <span>=</span><span>[]</span>
<span>for</span> <span>n</span> <span>in</span> <span>range</span><span>(</span><span>1</span><span>,</span> <span>sh</span><span>.</span><span>nrows</span><span>):</span>
    <span>data</span><span>.</span><span>append</span><span>({</span><span>key</span><span>:</span> <span>sh</span><span>.</span><span>row_values</span><span>(</span><span>n</span><span>)[</span><span>n2</span><span>]</span> <span>for</span> <span>n2</span><span>,</span> <span>key</span> <span>in</span> <span>enumerate</span><span>(</span><span>keys</span><span>)})</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>                
import xlrd
from leopards import Q

wb = xlrd.open_workbook("data.xls")
sh = wb.sheets()[0]
keys = sh.row_values(0)
data =[]
for n in range(1, sh.nrows):
    data.append({key: sh.row_values(n)[n2] for n2, key in enumerate(keys)})
res = Q(data, {"age__gt": 15})                

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ClickHouse

clickhouse_connect library can be used to read data from ClickHouse as dictionaries as shown below.

<span>import</span> <span>clickhouse_connect</span>
<span>client</span> <span>=</span> <span>clickhouse_connect</span><span>.</span><span>get_client</span><span>(</span> <span>host</span><span>=</span><span>'</span><span>localhost</span><span>'</span><span>,</span>  <span>username</span><span>=</span><span>'</span><span>default</span><span>'</span><span>,</span><span>password</span><span>=</span><span>''</span> <span>)</span>
<span>rows</span> <span>=</span> <span>client</span><span>.</span><span>execute</span><span>(</span><span>"</span><span>SELECT * FROM TABLE</span><span>"</span><span>)</span>
<span>data</span> <span>=</span> <span>rows</span><span>.</span><span>named_results</span><span>()</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
<span>import</span> <span>clickhouse_connect</span>
<span>client</span> <span>=</span> <span>clickhouse_connect</span><span>.</span><span>get_client</span><span>(</span> <span>host</span><span>=</span><span>'</span><span>localhost</span><span>'</span><span>,</span>  <span>username</span><span>=</span><span>'</span><span>default</span><span>'</span><span>,</span><span>password</span><span>=</span><span>''</span> <span>)</span>
<span>rows</span> <span>=</span> <span>client</span><span>.</span><span>execute</span><span>(</span><span>"</span><span>SELECT * FROM TABLE</span><span>"</span><span>)</span>
<span>data</span> <span>=</span> <span>rows</span><span>.</span><span>named_results</span><span>()</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
import clickhouse_connect
client = clickhouse_connect.get_client( host='localhost',  username='default',password='' )
rows = client.execute("SELECT * FROM TABLE")
data = rows.named_results()
res = Q(data, {"age__gt": 15})

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MySQL

mysql-client library can be used to read data from MySQL as dictionaries as shown below.

<span>import</span> <span>MySQLdb</span>
<span>from</span> <span>MySQLdb.cursors</span> <span>import</span> <span>DictCursor</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>
<span>db</span><span>=</span><span>MySQLdb</span><span>.</span><span>connect</span><span>(</span><span>user</span><span>=</span><span>'</span><span>root</span><span>'</span><span>,</span><span>password</span><span>=</span><span>'</span><span>PASS</span><span>'</span><span>,</span> <span>database</span><span>=</span><span>"</span><span>db</span><span>"</span><span>,</span> <span>cursorclass</span><span>=</span><span>DictCursor</span><span>)</span>
<span>cursor</span> <span>=</span> <span>db</span><span>.</span><span>cursor</span><span>()</span>
<span>cursor</span><span>.</span><span>execute</span><span>(</span><span>"</span><span>SELECT * FROM TABLE</span><span>"</span><span>)</span>
<span>data</span> <span>=</span> <span>cursor</span><span>.</span><span>fetchall</span><span>()</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
<span>import</span> <span>MySQLdb</span>
<span>from</span> <span>MySQLdb.cursors</span> <span>import</span> <span>DictCursor</span>
<span>from</span> <span>leopards</span> <span>import</span> <span>Q</span>

<span>db</span><span>=</span><span>MySQLdb</span><span>.</span><span>connect</span><span>(</span><span>user</span><span>=</span><span>'</span><span>root</span><span>'</span><span>,</span><span>password</span><span>=</span><span>'</span><span>PASS</span><span>'</span><span>,</span> <span>database</span><span>=</span><span>"</span><span>db</span><span>"</span><span>,</span> <span>cursorclass</span><span>=</span><span>DictCursor</span><span>)</span>
<span>cursor</span> <span>=</span> <span>db</span><span>.</span><span>cursor</span><span>()</span>
<span>cursor</span><span>.</span><span>execute</span><span>(</span><span>"</span><span>SELECT * FROM TABLE</span><span>"</span><span>)</span>
<span>data</span> <span>=</span> <span>cursor</span><span>.</span><span>fetchall</span><span>()</span>
<span>res</span> <span>=</span> <span>Q</span><span>(</span><span>data</span><span>,</span> <span>{</span><span>"</span><span>age__gt</span><span>"</span><span>:</span> <span>15</span><span>})</span>
import MySQLdb
from MySQLdb.cursors import DictCursor
from leopards import Q

db=MySQLdb.connect(user='root',password='PASS', database="db", cursorclass=DictCursor)
cursor = db.cursor()
cursor.execute("SELECT * FROM TABLE")
data = cursor.fetchall()
res = Q(data, {"age__gt": 15})

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原文链接：Leopards with different file types