如何以不同格式從R的CSV文件中讀取一列值

Question

如何在R中將圖例用於以下數據

ID  Gender    Age   Site      Times
1   Male      24    Facebook     10
2   Female    24    Linkedin     10
3   Male      24    Twitter      10
4   Female    24    Myspace      10
5   Male      24    Facebook     10
6   Female    24    linkedin     10
7   Male      24    Facebook     10

讀取我使用過的CSV

pd.readcsv <- read.csv(file = "snsite.csv")

設計我使用的餅圖

pie(pd.freq[order(pd.freq,decreasing = T)],
col = c("Blue","Green","Yellow","Brown","Green"),
border = NA, main = "Site Usage")

現在要在右上角或左上角顯示圖例，如何從csv文件中以不同的形式讀取一列（Site）值並將其存儲在變量中並在圖例函數中使用？

Answer 1

我不確定從哪里獲得pd.freq對象，但是假設您試圖獲取一個餅圖，該餅圖顯示每個站點訪問了每個站點的次數，那么就可以解決問題。

# Read dataframe, I would recommend including the stringsAsFactors = FALSE argument to your read.csv command
pd.readcsv <- read.table(text = "ID  Gender    Age   Site      Times
                                  1   Male      24    Facebook     10
                                  2   Female    24    Linkedin     10
                                  3   Male      24    Twitter      10
                                  4   Female    24    Myspace      10
                                  5   Male      24    Facebook     10
                                  6   Female    24    linkedin     10
                                  7   Male      24    Facebook     10", 
                                  header = TRUE, stringsAsFactors = FALSE)

# Convert sites to lowercase for proper aggregation
pd.readcsv$Site <- sapply(pd.readcsv$Site, tolower)

# Get vector of unique site names
sites <- unique(pd.readcsv$Site)

# Create aggregate dataframe with total times per site
pd.SumSiteTimes <- aggregate(Times~Site, sum, data = pd.readcsv)

# Create vector for colors
colors <- c("Blue","Green","Yellow","Brown","Green")

# Create pie chart
pie(pd.SumSiteTimes$Times[order(pd.SumSiteTimes$Times,decreasing = T)],
    col = colors,
    border = NA, 
    main = "Site Usage")

# Add legend to the plot
legend("topright", sites, cex = .8, fill = colors)