1. R for Data Analysis

install.packages(c("tidyverse", "dplyr", "ggplot2", "readr", "data.table"))

library(tidyverse) 

library(dplyr)

library(ggplot2)

library(readr)

library(data.table)

df <- read.csv("data.csv")  # Load CSV file

str(df)  # Check structure

summary(df)  # Summary statistics

head(df)  # First 6 rows
Data Cleaning


			

                

                    

                        

                        

                        

                    
                    

                        
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df <- df %>% drop_na()  # Remove missing values

df <- df %>% rename(new_name = old_name)  # Rename column

df$category <- as.factor(df$category)  # Convert column type

df <- df %>% mutate(new_column = column1 + column2)  # Create new column

df_filtered <- df %>% filter(Salary > 50000)  # Filter rows

df_sorted <- df %>% arrange(desc(Salary))  # Sort descending

df_summary <- df %>%

group_by(Department) %>%

summarise(Avg_Salary = mean(Salary, na.rm=TRUE))

2. Data Visualization in R (ggplot2)

ggplot(df, aes(x=Department, y=Salary)) +

geom_bar(stat="identity", fill="blue")

ggplot(df, aes(x=Salary)) +

geom_histogram(bins=30, fill="green", color="black")

ggplot(df, aes(x=Experience, y=Salary)) +

geom_point() +

geom_smooth(method="lm", col="red")

3. Tableau for Data Visualization

1. Connect Data: Import CSV, Excel, SQL Server, or Cloud data
2. Prepare Data: Use “Data Interpreter” to clean messy data
3. Create Charts:
   • Drag & drop Dimensions (Categories) and Measures (Numerical)
   • Choose visualization types (Bar Chart, Pie Chart, Heatmap, etc.)
4. Build a Dashboard:
   • Combine multiple charts
   • Use Filters, Parameters, and Actions for interactivity
5. Publish & Share:
   • Save to Tableau Public or Server
   • Export as PDF, Image, or Web Report

IF [Sales] > 5000 THEN "High" ELSE "Low" END

4. Power BI for Business Intelligence

1. Load Data: Connect to Excel, SQL, Cloud, APIs
2. Transform Data: Use Power Query to clean & reshape
3. Build Visualizations:
   • Drag fields into Reports View
   • Select chart types & apply filters
4. Create Dashboards:
   • Combine multiple reports
   • Add Slicers, Filters, and Drill-Throughs
5. Publish Reports:
   • Share via Power BI Service
   • Embed in websites or applications

Total_Sales = SUM(Sales[Revenue])

Avg_Salary = AVERAGE(Employees[Salary])

Sales_Percentage = DIVIDE([Total_Sales], SUM(Sales[Total]), 0)

5. Key Differences: Tableau vs Power BI

6. Data Analyst Best Practices

• Data Cleaning: Handle missing values, remove duplicates.
• Data Exploration: Identify patterns & trends before visualization.
• Use Filters & Slicers: Allow users to interact with reports.
• Automate Reports: Schedule updates in Power BI & Tableau.
• Optimize Performance: Reduce data load & improve dashboard speed

7. Learning Resources

8. Networking Basics

• Router: Connects different networks (e.g., LAN to WAN)
• Switch: Connects devices within a LAN
• Firewall: Controls incoming/outgoing traffic based on security rules
• Hub: Broadcasts traffic to all devices
• Access Point (AP): Wireless device that connects clients to a wired network

• IPv4: 32-bit, e.g., 192.168.1.1
• IPv6: 128-bit, e.g., 2001:db8::ff00:42:8329

• Subnet Mask: Defines the network & host portions
• CIDR Notation: /24 means 255.255.255.0
• Formula:
  • Hosts per subnet: 2^(32 – subnet bits) – 2
  • Subnets available: 2^borrowed bits

• IP Address: 192.168.1.10/24
• Subnet Mask: 255.255.255.0
• Network ID: 192.168.1.0
• Broadcast Address: 192.168.1.255
• Hosts per subnet: 254

9. Routing & Switching

• Static Routing: Manually configured routes
• Dynamic Routing: Protocols like RIP, OSPF, EIGRP, BGP

• MAC Address Table: Stores device MAC addresses
• VLAN (Virtual LAN): Segments network traffic logically
• Trunking (802.1Q): Allows multiple VLANs on one link
• STP (Spanning Tree Protocol): Prevents loops

bash

Switch(config)# vlan 10

Switch(config-vlan)# name Sales

Switch(config-vlan)# exit

Switch(config)# interface fastEthernet 0/1

Switch(config-if)# switchport mode access

Switch(config-if)# switchport access vlan 10

bash

Switch(config)# interface fastEthernet 0/2

Switch(config-if)# switchport mode trunk

Switch(config-if)# switchport trunk allowed vlan 10,20

10. Network Security

• AAA (Authentication, Authorization, Accounting)
• ACL (Access Control Lists): Filters network traffic
• Firewall: Blocks/Allows traffic based on rules
• VPN (Virtual Private Network): Encrypts remote connections

bash

Router(config)# access-list 10 permit 192.168.1.0 0.0.0.255

Router(config)# interface fastEthernet 0/0

Router(config-if)# ip access-group 10 in

Router(config)# access-list 100 permit tcp any host 192.168.1.1 eq 80

Router(config)# interface fastEthernet 0/0

Router(config-if)# ip access-group 100 in

11. Network Automation & Troubleshooting

bash

show ip interface brief  # Check interfaces

show running-config  # View running config

show vlan brief  # VLAN details

bash

debug ip route  # Monitor routing updates

debug arp  # Check ARP activity

bash

copy running-config startup-config

12. CCNA Exam Tips & Study Resources

•  Understand subnetting and practice IP calculations.
• Memorize key Cisco CLI commands..
• Practice VLANs, ACLs, and routing configurations.
•  Use Packet Tracer or GNS3 for hands-on labs.
•  Watch Cisco learning videos and read official study guides

• Cisco CCNA 200-301 Official Cert Guide
• Cisco Packet Tracer for simulations
• NetworkChuck (YouTube)
• Wendell Odom’s CCNA Study Guide
• Boson CCNA Practice Tests VLAN Configuration

bash

Switch(config)# vlan 10

Switch(config-vlan)# name Sales

Switch(config-vlan)# exit

Switch(config)# interface fastEthernet 0/1

Switch(config-if)# switchport mode access

Switch(config-if)# switchport access vlan 10

bash

Switch(config)# interface fastEthernet 0/2

Switch(config-if)# switchport mode trunk

Switch(config-if)# switchport trunk allowed vlan 10,20

bash

Router(config)# ip route 192.168.2.0 255.255.255.0 192.168.1.

13. Troubleshooting Commands

14. Network Automation

show ip interface brief  # View interface status

show running-config  # View current configuration

show vlan brief  # View VLAN configuration