類別2d密度圖

Question

我正在嘗試製作一個2d密度圖，其中爲每個類別顯示密度。例如，在下面的圖片中，我們每天都有一個密度圖，並且所有的每日密度都合併到彩色圖中。這些類型的地塊在關於大氣科學和氣溶膠污染研究的科學文獻中很常見。

到目前爲止，我已經有了這個

ggplot(dat, aes(y = `dN/dlogDp`, x = date)) + 
    stat_density2d(geom="tile", aes(fill = ..density..), contour = FALSE) + 
    scale_fill_gradient(low="blue", high="red") + 
    geom_point(alpha = 0.1) + 
    theme_bw() 

但我想天突間吧，我不知道從哪裏開始。

下面是示例數據：

structure(list(date = structure(c(1359244800, 1359245400, 1359246000, 
1359246600, 1359247200, 1359247800, 1359248400, 1359249000, 1359249600, 
1359250200, 1359250800, 1359251400, 1359252000, 1359252600, 1359253200, 
1359253800, 1359254400, 1359255000, 1359255600, 1359256200, 1359256800, 
1359257400, 1359258000, 1359258600, 1359259200, 1359259800, 1359260400, 
1359261000, 1359261600, 1359262200, 1359262800, 1359263400, 1359264000, 
1359264600, 1359265200, 1359265800, 1359266400, 1359267000, 1359267600, 
1359268200, 1359268800, 1359269400, 1359270000, 1359270600, 1359271200, 
1359271800, 1359272400, 1359273000, 1359273600, 1359274200, 1359274800, 
1359275400, 1359276000, 1359276600, 1359277200, 1359277800, 1359278400, 
1359279000, 1359279600, 1359280200, 1359280800, 1359281400, 1359282000, 
1359282600, 1359283200, 1359283800, 1359284400, 1359285000, 1359285600, 
1359286200, 1359286800, 1359287400, 1359288000, 1359288600, 1359289200, 
1359289800, 1359290400, 1359291000, 1359291600, 1359292200, 1359292800, 
1359293400, 1359294000, 1359294600, 1359295200, 1359295800, 1359296400, 
1359297000, 1359297600, 1359298200, 1359298800, 1359299400, 1359300000, 
1359300600, 1359301200, 1359301800, 1359302400, 1359303000, 1359303600, 
1359304200), class = c("POSIXct", "POSIXt"), tzone = "UTC"), 
    `dN/dlogDp` = c(49.8, 49.275, 47.4, 47.975, 48.625, 51.725, 
    50.7, 47.55, 45.975, 45.35, 45.4, 47.75, 49.625, 48.225, 
    47.65, 47.3, 48.75, 50.075, 34.725, 42.025, 48.825, 52.25, 
    54.05, 49.15, 34.6, 34.375, 42.85, 30.325, 43.15, 36.875, 
    32.85, 36.85, 35.725, 39.8, 38.65, 40.1, 42.675, 38.5, 37.2, 
    34.425, 25.2, 14.725, 22.675, 14.875, 37.45, 46.025, 49.275, 
    35.425, 30, 38.9, 28.6, 41.675, 46.05, 48.6, 62.425, 62.65, 
    61.7, 49.5, 70.05, 71.875, 59.4, 38.525, 36.85, 25.625, 14.675, 
    14.7, 14.6, 14.725, 15.6, 15, 14.6, 14.75, 15.05, 14.975, 
    15.425, 15.1, 15.95, 14.95, 15, 14.6, 14.725, 14.85, 15.175, 
    28.95, 14.975, 14.725, 16.6, 18.925, 53.225, 60.2, 56.425, 
    54.55, 41.4, 19.025, 19.825, 31.875, 14.85, 16.375, 16.65, 
    34.325), Diameter = c(14.6, 15.1, 15.7, 16.3, 16.8, 17.5, 
    18.1, 18.8, 19.5, 20.2, 20.9, 21.7, 22.5, 23.3, 24.1, 25, 
    25.9, 26.9, 27.9, 28.9, 30, 31.1, 32.2, 33.4, 34.6, 35.9, 
    37.2, 38.5, 40, 41.4, 42.9, 44.5, 46.1, 47.8, 49.6, 51.4, 
    53.3, 55.2, 57.3, 59.4, 61.5, 63.8, 66.1, 68.5, 71, 73.7, 
    76.4, 79.1, 82, 85.1, 88.2, 91.4, 94.7, 98.2, 101.8, 105.5, 
    109.4, 113.4, 117.6, 121.9, 126.3, 131, 135.8, 140.7, 145.9, 
    151.2, 156.8, 162.5, 168.5, 174.7, 181.1, 187.7, 194.6, 201.7, 
    209.1, 216.7, 224.7, 232.9, 241.4, 250.3, 259.5, 269, 278.8, 
    289, 299.6, 310.6, 322, 333.8, 346, 358.7, 371.8, 385.4, 
    399.5, 414.2, 429.4, 445.1, 461.4, 478.3, 495.8, 514)), .Names = c("date", 
"dN/dlogDp", "Diameter"), row.names = c(NA, 100L), class = c("tbl_df", 
"tbl", "data.frame")) 

UPDATE這個問題是錯誤的，我現在認爲，使用類別不相關的重建該地塊。這些其他問題都更密切相關的重建該地塊的任務：

• geom_raster interpolation with log scale
• Use R to recreate contour plot made in Igor

後，我問這個問題，我一直保持的R代碼裏面，結合更新的要點從這些問題的答案中獲得詳細信息，併成功複製這些圖（包含在要點中的示例輸出）。該要點如下：https://gist.github.com/benmarwick/9a54cbd325149a8ff405

Answer 1

關鍵步驟是去掉面板上的大部分裝飾，並使用scale_*_continuous(expand = c(0,0))使密度圖填充整個面板。這裏有一個如何把它一起的例子：

# get the day and hour to use as facet panels 
dat$day <- as.Date(dat$date) 
dat$hour <- as.numeric(format(dat$date, "%H")) 

library(ggplot2) 
library(viridis) 

# theme to suppress many details 
squeeze_grid_theme <- theme_bw() + theme(axis.title = element_blank(), 
          axis.ticks = element_blank(), 
          axis.text = element_blank(), 
          strip.text = element_blank(), 
          strip.background = element_blank(), 
          panel.margin.y = unit(0, "lines"), 
          panel.margin.x = unit(-1,"lines"), 
          panel.border = element_blank(), 
          panel.grid = element_blank(), 
          axis.text.x = element_text(margin=margin(0,0,0,0,"pt")), 
          axis.text.y = element_text(margin=margin(0,0,0,0,"pt"))) 

p <- ggplot(dat, aes(z = Diameter, y = `dN/dlogDp`, x = date)) + 
    stat_density2d(geom="tile", aes(fill = ..density..), contour = FALSE) + 
    scale_fill_viridis() + 
    geom_point(alpha = 0.1) + 
    facet_grid(~hour) + 
    scale_y_continuous(expand = c(0,0)) + 
    scale_x_datetime(expand = c(0,0)) + 
    squeeze_grid_theme 

p 

然後我們得到每個小時的單獨密度圖，緊緊地擠在一起，就像在討論的示例圖。