如何显示六边形填充颜色的图例？

我正在 ggplot2 中绘制十六进制图。出现的图例是关于六边形的填充（计数），而不是关于六边形实际热缩放的内容（预测）。

我如何摆脱计数的图例，但让它显示实际热缩放的内容（预测）。这是我的代码和我所指内容的图片。

FF1xBARHH <- ggplot(FFxBARHH, aes(x = plate_x, y = plate_z, z = Prediction)) +
  stat_summary_hex(fun = mean, bins = 9) +
  stat_summary_hex(geom = "text", aes(label = after_stat(value)), fun = length, 
                   bins = 9) +
  scale_fill_gradient2(low = "blue", mid = "white", high = "red", midpoint = 0.240) +
  xlim(c(2,-2)) +
  ylim(c(0,5)) +
  coord_fixed(0.8)+
  labs(title = "Gerrit Cole Fastball April 2022 ExAVG Map RHH")+
  annotate('rect', xmin = -0.85, xmax = 0.85, ymin = 1.6, ymax = 3.5, 
           fill = 'black', color = 'black', alpha = 0.0001, size = 1)

FFxBARHH <- structure(list(Prediction = c(0.002, 0.598, 0, 0, 0.688, 0.104, 
0.908, 0.042, 0.142, 0.872, 0.034, 0.916, 0, 0, 0, 0, 0, 0, 0, 
0, 0, 0), pitch_type = c("FF", "FF", "FF", "FF", "FF", "FF", 
"FF", "FF", "FF", "FF", "FF", "FF", "FF", "FF", "FF", "FF", "FF", 
"FF", "FF", "FF", "FF", "FF"), game_date = structure(c(19112, 
19112, 19112, 19106, 19106, 19095, 19095, 19095, 19095, 19095, 
19095, 19090, 19112, 19112, 19112, 19106, 19106, 19095, 19095, 
19095, 19083, 19083), class = "Date"), release_speed = c(97.9, 
96.6, 96.2, 98, 95.4, 99.8, 97.5, 97.6, 96.8, 95.7, 94.7, 99.1, 
98.7, 98.1, 96.2, 97.7, 98.6, 99.3, 98.9, 97.9, 96.2, 96.8), 
    player_name = c("Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", 
    "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", 
    "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", 
    "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", 
    "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit", 
    "Cole, Gerrit", "Cole, Gerrit", "Cole, Gerrit"), pitcher = c(543037, 
    543037, 543037, 543037, 543037, 543037, 543037, 543037, 543037, 
    543037, 543037, 543037, 543037, 543037, 543037, 543037, 543037, 
    543037, 543037, 543037, 543037, 543037), events = c("field_out", 
    "single", "field_out", "field_out", "field_out", "field_out", 
    "double", "field_out", "field_out", "double", "field_out", 
    "double", "strikeout", "strikeout", "strikeout", "strikeout", 
    "strikeout", "strikeout", "strikeout", "strikeout", "strikeout", 
    "strikeout"), description = c("hit_into_play", "hit_into_play", 
    "hit_into_play", "hit_into_play", "hit_into_play", "hit_into_play", 
    "hit_into_play", "hit_into_play", "hit_into_play", "hit_into_play", 
    "hit_into_play", "hit_into_play", "called_strike", "swinging_strike", 
    "called_strike", "called_strike", "foul_tip", "foul_tip", 
    "swinging_strike", "called_strike", "called_strike", "called_strike"
    ), zone = c(2, 2, 1, 2, 2, 9, 8, 7, 6, 5, 2, 2, 6, 4, 9, 
    9, 5, 6, 5, 9, 8, 6), des = c("Edward Olivares grounds out, second baseman Gleyber Torres to first baseman Anthony Rizzo.", 
    "Bobby Witt Jr.  singles on a sharp line drive to center fielder Aaron Hicks.", 
    "Bobby Witt Jr.  flies out to right fielder Giancarlo Stanton.", 
    "Oscar Mercado pops out to first baseman Anthony Rizzo in foul territory.", 
    "Owen Miller grounds out, second baseman Gleyber Torres to first baseman Anthony Rizzo.", 
    "Teoscar Hernandez grounds out, second baseman Gleyber Torres to first baseman Anthony Rizzo.   Vladimir Guerrero Jr.  to 3rd.", 
    "Vladimir Guerrero Jr.  doubles (1) on a line drive to right fielder Aaron Judge.", 
    "Alejandro Kirk grounds out sharply, shortstop Isiah Kiner-Falefa to first baseman Anthony Rizzo.", 
    "Lourdes Gurriel Jr.  grounds out sharply, second baseman Gleyber Torres to first baseman Anthony Rizzo.", 
    "Bo Bichette doubles (1) on a sharp line drive to center fielder Aaron Hicks.", 
    "Santiago Espinal flies out sharply to center fielder Aaron Hicks.", 
    "J.D. Martinez doubles (1) on a line drive to right fielder Aaron Judge.   Xander Bogaerts scores.", 
    "Bobby Witt Jr.  called out on strikes.", "Salvador Perez strikes out swinging.", 
    "Hunter Dozier called out on strikes.", "Amed Rosario called out on strikes.", 
    "Myles Straw strikes out on a foul tip.", "George Springer strikes out on a foul tip.", 
    "Matt Chapman strikes out swinging.", "Bo Bichette called out on strikes.", 
    "Jonathan Schoop called out on strikes.", "Miguel Cabrera called out on strikes."
    ), stand = c("R", "R", "R", "R", "R", "R", "R", "R", "R", 
    "R", "R", "R", "R", "R", "R", "R", "R", "R", "R", "R", "R", 
    "R"), plate_x = c(0.07, 0.19, -0.62, 0.07, 0.24, 0.75, 0.21, 
    -0.42, 0.29, -0.19, -0.22, -0.2, 0.55, -0.3, 0.82, 0.46, 
    -0.03, 0.71, -0.24, 0.52, 0.1, 0.66), plate_z = c(3.26, 3.48, 
    3.08, 2.94, 2.74, 2.17, 2.01, 1.85, 2.58, 2.56, 2.75, 3.18, 
    2.41, 2.43, 1.75, 1.64, 2.73, 2.37, 2.34, 1.85, 1.93, 2.81
    ), launch_speed = c(95.9, 105.1, 86.2, 72.9, 106.7, 95.4, 
    91.8, 101.2, 104.2, 109.8, 100.4, 91.9, NA, NA, NA, NA, NA, 
    NA, NA, NA, NA, NA), launch_angle = c(-10, 15, 56, 68, 4, 
    -15, 9, -10, 0, 13, 36, 12, NA, NA, NA, NA, NA, NA, NA, NA, 
    NA, NA)), row.names = c(NA, -22L), class = c("data.table", 
"data.frame"), .internal.selfref = <pointer: 0x7fbc9f01eee0>)

这里的问题是预测（平均值）和计数都一起显示在一个调色板中。如果您为涵盖 Preditions 范围的调色板定义限制（我使用limits = c(-.1, .6)）那么情节看起来就如你所料，对吧？

ggplot(FFxBARHH, aes(x = plate_x, y = plate_z, z = Prediction))+
  stat_summary_hex(fun = mean, bins = 9) +
  stat_summary_hex(geom = "text", aes(label = after_stat(value)), fun = length,
                   bins = 9) +
  scale_fill_gradient2(low = "blue", mid = "white", high = "red", 
                        midpoint = 0.240, 
                        limits = c(-.1, .6)) +
  xlim(c(2,-2)) +
  ylim(c(0,5)) +
  coord_fixed(0.8)+
  labs(title = "Gerrit Cole Fastball April 2022 ExAVG Map RHH")+
  annotate('rect', xmin = -0.85, xmax = 0.85, ymin = 1.6, ymax = 3.5, 
           fill = 'black', color = 'black', alpha = 0.0001, size = 1)