Cannot create line and points on my plot

Question

I don't know why but R doesn't allow me to add a line and points on my plot (i.e. pch, lty and lwt don't work)

The x-axis values are factors. I just want to create a line with the observed values.

Why is this happening?

Here my code:

> df
   Var1 Freq
1   Oct 234
2   Nov 100
3   Dec 1653
4   Jan 800
5   Feb 960
6   Mar 1182
7   Apr  389
8   May 1333
9   Jun 2251
10  Jul 2221
11  Aug 1012
12  Sep  362

x1 = factor(df$Var1, levels = c('Oct', 'Nov', 'Dec', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep'))

df$Freq = as.numeric(as.character(df$Freq))

plot(x1, df$Freq, type = 'b')

Answer 1

Is this what you're after?

# The sample data
df <- cbind.data.frame(
    Var1 = c("Oct","Nov","Dec","Jan","Feb","Mar","Apr","May","Jun","Jul","Aug","Sep"),
    Freq = c(1101, 1158, 1753, 1918, 1296, 682, 389, 333, 251, 221, 312, 362));

x1 = factor(df$Var1, levels = c('Oct', 'Nov', 'Dec', 'Jan', 'Feb', 'Mar', 'Apr', 'May', 'Jun', 'Jul', 'Aug', 'Sep'))

# This has no purpose as df$Freq is already numeric
df$Freq = as.numeric(as.character(df$Freq))

# Turn x1 factors into numeric values and  
# plot as line plot without x-axis labels
plot(as.numeric(x1), df$Freq, type = 'l', 
    xaxt = "n", 
    xlab = "Month", 
    ylab = "Freq");
# Add custom x-axis with labels 
# given by the levels of x1
axis(1, at = as.numeric(x1), labels = as.character(x1));

# Alternatively: Plot with points and line
plot(as.numeric(x1), df$Freq, type = 'b', 
    xaxt = "n", 
    xlab = "Month", 
    ylab = "Freq");
axis(1, at = as.numeric(x1), labels = as.character(x1));