Order the legend names in ggplot2 object from smaller to larger - r

Question

I have the dataframe below and I want to set the order of the legend names from smaller to larger. The values may be characters but they have correspondence to the Cases column which I believe could be useful since the dataset is dynamic.
Cum<-structure(list(Age.group = c("00-04", "00-04", "05-14", "05-14",
"15-24", "15-24", "25-49", "25-49", "50-64", "50-64", "65-79",
"65-79", "80+", "80+"), Gender = c("Female", "Male", "Female",
"Male", "Female", "Male", "Female", "Male", "Female", "Male",
"Female", "Male", "Female", "Male"), Cases = c(64578, 70518,
187568, 197015, 414405, 388138, 1342394, 1206168, 792180, 742744,
400232, 414613, 282268, 198026), lab = c("64,578", "70,518",
"187,568", "197,015", "414,405", "388,138", "1,342,394", "1,206,168",
"792,180", "742,744", "400,232", "414,613", "282,268", "198,026"
), Age.group.Sum = c(135096, 135096, 384583, 384583, 802543,
802543, 2548562, 2548562, 1534924, 1534924, 814845, 814845, 480294,
480294), lab2 = c("135,096", "135,096", "384,583", "384,583",
"802,543", "802,543", "2,548,562", "2,548,562", "1,534,924",
"1,534,924", "814,845", "814,845", "480,294", "480,294"), color = c("#4285f4",
"#4285f4", "#90a9e0", "#90a9e0", "#dd9e5f", "#dd9e5f", "#b45f06",
"#b45f06", "#b45f06", "#b45f06", "#dd9e5f", "#dd9e5f", "#aebbd6",
"#90a9e0"), Range = c("LESS THAN 74.5K", "LESS THAN 74.5K", "148.9K - 223.4K",
"148.9K - 223.4K", "372.3K - 446.7K", "372.3K - 446.7K", "MORE THAN 670.1K",
"MORE THAN 670.1K", "MORE THAN 670.1K", "MORE THAN 670.1K", "372.3K - 446.7K",
"372.3K - 446.7K", "223.4K - 297.8K", "148.9K - 223.4K")), class = "data.frame", row.names = c(NA,
-14L))
names(mycols) <- mycols
ylab <- c(0.5,1,1.5,2,2.5)
lbls <- setNames(unique(Cum$color), unique(Cum$Range))
ggplot_obj <- ggplot(data = Cum, aes(x = `Age.group`, y = Cases, group = Gender,fill = Range)) +
geom_bar(aes(
text = paste("<b>Gender:</b>", Gender, "<br><b>Age:</b>", `Age.group` ,
"<br><b>Cases:</b>", lab, "<br><b>Total cases in age group:</b>",
lab2)),
position = "dodge", stat = "identity") +
geom_text(aes(y = Cases + 10000, label = Gender), vjust = 1,
position = position_dodge(width=0.9),size=2) +
scale_fill_manual(values = lbls) +
coord_cartesian(ylim = c(0, max(Cum$Cases)*1.1), expand = FALSE) +
theme_bw()+ theme(
# remove the vertical grid lines
panel.grid.major.x = element_blank(),
panel.border = element_blank(), axis.line.x = element_line()
) +
scale_y_continuous(labels = unit_format(unit = "M", scale = 1e-6))+
xlab("Age group")

Answer 1

We could convert the column to factor with levels specified in the custom order
Cum$Range <- factor(Cum$Range, levels = c("LESS THAN 74.5K" , "148.9K - 223.4K" , "223.4K - 297.8K", "372.3K - 446.7K" , "MORE THAN 670.1K"))
ylab <- c(0.5,1,1.5,2,2.5)
lbls <- setNames(Cum$color[match(levels(Cum$Range), Cum$Range)], levels(Cum$Range))
Construct the plot with ggplot as in the OP's code
-output
Update
If the 'Range' values are dynamic (assuming the unit is the same), then extract the numeric part with parse_number, order and get the unique values
lvls <- as.character(unique(Cum$Range[order(readr::parse_number(as.character(Cum$Range)))]))
Cum$Range <- factor(Cum$Range, levels = lvls)
Or another option is to arrange by 'Cases` and set the levels for 'Range'
library(dplyr)
Cum <- Cum %>%
arrange(Cases, Age.group) %>%
mutate(Range = factor(Range, levels = unique(Range)))
lbls <- setNames(Cum$color[match(levels(Cum$Range), Cum$Range)], levels(Cum$Range))